title: Ara Pacis

text: The altar reflects the Augustan vision of Roman civil religion. The lower register of its frieze depicts agricultural work meant to communicate the abundance and prosperity of the Roman Peace (). The monument as a whole serves a dual civic ritual and propaganda function for Augustus and his regime, easing notions of autocracy and dynastic succession that might otherwise be unpalatable to traditional Roman culture.


title: Ara Pacis

text: The monument consists of a traditional open-air altar at its centre surrounded by precinct walls which are pierced on the eastern and western ends (so called today because of the modern layout) by openings and elaborately and finely sculpted entirely in Luna marble.


title: Ara Pacis

text: Within the enclosing precinct walls, the altar itself was carved with images illustrating the "lex aria", the law governing the ritual performed at the altar. The sacrificial procession depicts animals being led to sacrifice by figures carved in a Republican style similar to the so-called "Altar of Domitius Ahenobarbus", in sharp contrast with the style on the exterior of the precinct walls. What remains of the altar is otherwise fragmentary, but it appears to have been largely functional with less emphasis on art and decoration.


title: Ara Pacis

text: The interior of the precinct walls are carved with bucrania, ox skulls, from which carved garlands hang. The garlands bear fruits from various types of plants, all displayed on a single garland as allegorical representations of plenty and abundance. The bucrania in turn evoke the idea of sacrificial piety, appropriate motifs for the interior of the altar precinct. The lower register of the interior walls imitate the appearance of traditionally wooden altar precincts, which were meant to bring to mind other such altars in Rome and the tradition of constructing altars at the boundary of the city's "pomerium."


title: Ara Pacis

text: The exterior walls of the Ara Pacis are divided between allegorical and pseudo-historical relief panels on the upper register while the lower register comprises scenes of nature: harmonic, intertwined vines that contain wildlife and connote nature under control. The upper register of the northern and southern walls depict scenes of the emperor, his family, and members of the regime in the act of processing to or performing a sacrifice. Various figures in togas are shown with their heads covered ("capite velato"), signifying their role as both priests and sacrificiants. Other figures wear laurel crowns, traditional Roman symbols of victory. Members of individual priestly colleges are depicted in traditional garb appropriate to their office, while lictors can be identified by their iconographic "fasces". Women and children are also included among the procession; the depiction of children in Roman sculpture would have been novel at the time of the Altar's construction, evoking themes of moral and familial piety, as well as easing concerns over dynastic intentions while simultaneously introducing potential heirs to the public eye. However, despite the emphasis on family values, the anonymity of many of the women depicted enforces the male retention of power within this new age of peace.


title: Ara Pacis

text: The western and eastern walls are both pierced by entryways to the altar, although the interior would only have been accessed by a stairway on the western side. The entryways were flanked by panels depicting allegorical or mythological scenes evocative of peace, piety and tradition. On the eastern wall, panels depicted the seated figures of Roma and Pax, while the western side depicts the discovery of the twins and she-wolf and the sacrifice of a figure traditionally identified as Aeneas, but increasingly believed to be Rome's second king, Numa Pompilius. The identity of these various figures has been a point of some controversy over the years, relying heavily on interpretation of fragmentary remains, discussed below.


title: Ara Pacis

text: The sculpture of the Ara Pacis is primarily symbolic rather than decorative, and its iconography has several levels of significance. Studies of the Ara Pacis and similar public Roman monuments traditionally address the potent political symbolism of their decorative programs, and their emphasis and promulgation of dynastic and other imperial policies; they are usually studied as a form of imperial propaganda. The Ara Pacis is seen to embody without conscious effort the deep-rooted ideological connections among cosmic sovereignty, military force, and fertility that were first outlined by Georges Dumézil, connections which are attested in early Roman culture and more broadly in the substructure of Indo-European culture at large. Peter Holliday suggested that the Altar's imagery of the Golden Age, usually discussed as mere poetic allusion, appealed to a significant component of the Roman populace. The program of the Ara Pacis addressed this group's very real fears of cyclical history, and promised that the rule of Augustus would avert the cataclysmic destruction of the world predicted by contemporary models of historical thought.


title: Ara Pacis

text: The East and West walls each contain two panels, one well preserved and one represented only in fragments.


title: Ara Pacis

text: The East Wall contains a badly preserved scene of a female warrior (), possibly Roma, apparently sitting on a pile of weapons confiscated from the enemy (war trophy), thus forcing peace upon them by rendering them unable to make war. This scene has been reconstructed, based on coins that depict such a seated Roma. When the monument was being reconstructed at its present site, Edmund Buchner and other scholars sketched what the panel may have looked like. This interpretation, although widely accepted, can not be proved correct, as so little of the original panel survives.


title: Ara Pacis

text: The other panel is more controversial in its subject, but far better preserved. A goddess sits amid a scene of fertility and prosperity with twins on her lap. Scholars have variously suggested that the goddess is Italia, Tellus (Earth), Venus Genetrix or Pax (Peace), although other views also circulate. Due to the widespread depiction around the sculpture of scenes of peace, and because the altar is named for "peace", the favoured conclusion is that the goddess is Pax.


title: Ara Pacis

text: The West Wall also contains two panels. The fragmentary "Lupercal Panel" apparently preserves the moment when Romulus and Remus were discovered by Faustulus the shepherd, while Mars looks on. Again this panel is a modern drawing without much evidence. Marble fragments of the tree and the head and shoulder of Mars (if it is Mars) and part of a second individual (thought to be Faustulus) survive, but the addition of the she-wolf, Romulus, and Remus is entirely speculative.


title: Ara Pacis

text: The better preserved scene depicts the sacrifice of a pig (the standard sacrifice when Romans made a peace treaty) by an old priest and two attendants. In 1907, this scene was identified by Johannes Sieveking as the moment when Aeneas, newly arrived in Italy, sacrificed a sow and her 30 piglets to Juno, as told by Virgil and others, even though the scene differs greatly from Vergil's description. In the 1960s, Stephan Weinstock challenged this identification (and the very identity of the entire monument), citing numerous discrepancies that Sieveking and his followers had failed to notice between Vergil's version and the panel. Subsequently, the suggestion was made that the scene shows Numa Pompilius, the Roman king associated with Peace and the Gates of Janus. Paul Rehak later published an article with this proposal, confirmed in a chapter of his posthumous book. This theory has won over many scholars, despite considerable initial resistance.


title: Ara Pacis

text: The long friezes of the Ara Pacis (the North and South Walls) contain figures advancing towards the West, who participate in a state of thanksgiving to celebrate the Peace created by Augustus. These figures fall into four categories: lictors (men carrying fasces, bodyguards of magistrates); priests (three of the four major "collegia" – "Pontifices", "Septemviri", and "Quindecimviri"): women and children (generally from the imperial family, represented in portraiture); and attendants (a few anonymous figures necessary for religious purposes).


title: Ara Pacis

text: In addition there are two or three non-Roman children, who may be guests (or hostages) in Rome. Their identification by their non-Roman costume and their participation in the ceremony advertises to all that Rome is the centre of the world, and that other nations send their young to Rome to learn Roman ways, so great is Rome's reputation. The ceremony took place in the summer of 13 BC, but not necessarily on 4 July, when the Senate voted to build the Ara Pacis.


title: Ara Pacis

text: The north wall has about 46 extant or partially extant figures. The first two foreground figures are lictors, carrying fasces (bundles of rods symbolizing Roman authority). The next set of figures consists of priests from the college of the Septemviri epulones, so identified by an incense box they carry with special symbols. One member of this college is missing in a gap.


title: Ara Pacis

text: After them follows the "collegium" of the "quindecimviri sacris faciundis", also identified by the incense box carried by a public slave among them. Although the name suggests this college has exactly fifteen members, the size of the college has grown to 23, including Augustus and Agrippa, who appear on the South Frieze. The other twenty-one members are present here. Two very badly damaged figures in the middle are split by a gap. From photos, the gap appears to affect a single figure, but as Koeppel, Conlin, and Stern have proven, in-site examination reveals that one is a foreground and the other a background figure.


title: Ara Pacis

text: The last portion of the North Frieze consists of members of the imperial family. Many scholars used to identify the veiled, leading figure as Julia, daughter of Augustus, but since Julia appears on the South Frieze, it is more likely that this figure is Octavia Minor. Other figures in the entourage might include Marcella Major (a daughter of Octavia), Iullus Antonius (a son of Mark Antony), and two boys and a girl of the imperial family.


title: Ara Pacis

text: In 1894, and again in 1902 and 1903, Eugen Petersen suggested that Lucius Caesar appears with Agrippa, dressed in a "Trojan" costume for the Troy Game held in 13 BC (see below). Many scholars, realizing by 1935 that Lucius was too young to be the boy beside Agrippa, preferred to identify him as Gaius. They named the smallest child on the North Frieze "Lucius," even though he is a mere toddler (Lucius was four in 13 BC). Some scholars assumed this boy also was a participant in the Troy Games, although he is certainly too young (six or seven was the minimum age). If this toddler were Lucius, he would be too young and in the wrong costume for the Troy Games. The best guess is that he is a Germanic tribal prince, but he is certainly not a dressed as a Trojan. As Charles Brian Rose has noted, "The variable value of the Eastern costume and the uneasy interaction of Trojan and Parthian iconography can make it difficult to determine whether one is viewing the founders of the Romans or their fiercest opponents."


title: Ara Pacis

text: The youth wearing Hellenistic Greek clothing suited to a Hellenistic prince has been identified as Gaius in the guise of a "camillus", an adolescent attendant of the Flamen Dialis. The Gaius identification is best supported by his size, however an additional boy in Roman dress who has a "bulla" (but has lost his head) is also the right size, and therefore a better guess. For Gaius to appear in public without his "bulla" would invite the evil eye. This same figure in Hellenistic dress has also been interpreted as Ptolemy of Mauretania representing Africa, along with the German boy (Europe) and the Parthian prince (Asia). A foreign prince would not wear a "bulla".


title: Ara Pacis

text: The South Wall has seen a great deal of scholarship and the greatest number of academic debates. Unlike the North Wall, where most of the heads are new (not authentic ancient heads, but modern creations), the heads of the figures on the South Wall are mostly original. Some half dozen figures are recognizable from looking at other surviving statues of members of the imperial family. Nevertheless, much debate has taken place over many of these figures, including Augustus, Agrippa, Tiberius, Julia, and Antonia.


title: Ara Pacis

text: The figure of Augustus was not discovered until the 1903 excavation, and his head was damaged by the cornerstone of the Renaissance palazzo built on top of the original Ara Pacis site. Although he was identified correctly in 1903, Petersen, Strong, and Stuart-Jones initially saw the figure as the "rex sacrorum". Today Augustus is better recognized by his hair style than his face.


title: Ara Pacis

text: In the absence of Augustus from the panel, early scholars debated whether Agrippa (the tall veiled priest) was Augustus or Agrippa or Lepidus. In 1907, Sieveking proposed that this figure was Lepidus, the "Pontifex Maximus" in 13 BC. Sieveking later reversed his position with a series of peculiar suggestions. In 1926, Loewy compared the Ara Pacis Agrippa to the Louvre Agrippa and the Agrippa in Copenhagen (and elsewhere) in order to demonstrate the iconographical similarity. Aside from a very small minority of scholars (most vehemently defensive of Lepidus in "Rom. Mitt" in the 1930s was Ludwig Curtius), the rest of the academy concluded that this figure is Agrippa. Ryberg's 1949 article gave further weight to that conclusion.


title: Ara Pacis

text: Many scholars continue to see the Julia figure as Livia, having reasoned that Livia has to be on the Ara Pacis. Indeed, Livia does appear somewhere (her exclusion is unlikely), but by 13 BC Julia had politically eclipsed Livia, as has been understood and explained by many scholars. The identification dates back to Milani in 1891. Furthermore, Livia has no bond to Agrippa, whereas Julia was his wife and expected to be the unofficial empress of Rome for decades, during and beyond Augustus' lifetime. Julia also better personified Augustus' new pro-natalism program, having already given birth to four surviving children (and was pregnant with a fifth). Surprisingly, a majority of scholars in 2000 preferred to see this figure as Livia.


title: Ara Pacis

text: The Tiberius figure was identified as such by Milani, an identification that was rarely questioned until the 1940s. Moretti, in making the glass museum for the Ara Pacis at Mussolini's command, guessed that the two consuls (Tiberius and Varus) of 13 flank Augustus, so he saw this figure as M. Valerius Messalla. V. H. von Poulsen and Toynbee proposed Iullus Antonius. But as has been well established, Augustus is flanked by priests, and this figure is Tiberius. Boschung and Bonanno have both matched the face to early period Tiberius statuary.


title: Ara Pacis

text: In relation to Antonia, Drusus, and Germanicus, H. Dütschke proposed in 1880 the correct identity for Antonia and Drusus, but incorrectly saw the toddler as Claudius. A. von Domaszewski amended this family identification and correctly saw the child as Germanicus. He also suggested that the Ara Pacis is arranged in family groups. He correctly determined that the two-year-old child could be only Germanicus, whose exact birth on 24 May 15 BC is known. This helps prove that the ceremony is an event in 13, although a few scholars continued to argue the ceremony was that of 9 BC (until definitive proof in favor of 13 came out in 1939).


title: Ara Pacis

text: In relation to the Domitii Ahenobarbi, von Domaszewski also proposed in the same 1903 article that the last family on the South Wall is that of the father of the emperor Nero (born Lucius Domitius Ahenobarbus). This identification remains widespread today. John Pollini provides the best summary of this viewpoint in his article, "Ahenobarbi, Appuleii and Some Others on the Ara Pacis", where he points out that the writer Suetonius specifically mentions that Nero's father went "to the East on the staff of the young Gaius Caesar". As this campaign is known to have begun in 2 BC, it means that Gnaeus must have been of mature age by that time, therefore requiring a birth year of at least 17 BC, which would, in turn, make him sufficiently old to be the boy on the Ara Pacis. Pollini also reasons that the delay in Gnaeus' career (only reaching the consulship in 32 AD) resulted from his documented unpleasant character and points out that the careers of other members of the family with undesirable traits also suffered similar delays, notably Augustus' youngest grandson, Agrippa Postumus, who had no career, and Germanicus' brother, the later emperor, Claudius, whose career started late. However, there are some dissenters from this theory. Stern claims that these figures cannot possibly be the Domitii Ahenobarbi, on the basis of the belief that Gnaeus Domitius Ahenobarbus, whom von Domaszewski saw as the boy of the family, was born after the monument's completion. Syme had also argued that Gnaeus was born after the monument's completion, but accepted the identification of the Ahenobarbus family, preferring to identify the boy as an otherwise unknown elder brother and the girl figure as an otherwise unknown elder sister of Gnaeus—both of whom died young. Syme also proved somewhat unintentionally, based on the inscription "ILS" 6095 that Lucius Domitius Ahenobarbus was governor of Africa in 13 BC and could not be in Rome for the Ara Pacis ceremony.


title: Ara Pacis

text: Starting in 1894, Eugen Petersen suggested that Lucius Caesar appears between Augustus (this veiled figure is actually Agrippa) and Livia (actually Julia). Petersen had a good idea about families grouping together, but he identified none of the figures correctly in this place. In the 1920s as more and more scholars decided the scene dates to 13 BC, Loewy proposed that Lucius was too young to be this boy. After Loewy's 1926 article, consensus shifted to Gaius Caesar. Gaius, seven years old in 13 BC, fit better. Moretti canonized that Gaius was dressed in a "Trojan" costume for the equestrian boys event called the Troy Game, which was held in 13 or possibly 11 BC for the dedication of the Theater of Marcellus. This theory won universal acceptance for many decades, even though the evidence is overwhelmingly against. The boy is clearly not a Roman, given his clothing, lack of "bulla", and hair style. So ingrained was Petersen's theory, however, that when the distinguished scholar Erika Simon (1968, 18) suggested the boy is a barbarian, she was subjected to intense criticism until she retracted. Subsequently, led by Charles Brian Rose and Ann Kuttner, North American scholars have realized Petersen was wrong: the boy is a foreign prince. Stern adds the costume is wrong for a Trojan (no Phrygian hat) and no "bulla" – worn by all Roman boys as protection from the evil eye. Many others have contributed to disprove Petersen's theory.


title: Ara Pacis

text: In 1938 the finally reconstructed Ara was placed near the Mausoleum of Augustus, and a big pavilion was built around it by architect Vittorio Ballio Morpurgo as part of Benito Mussolini's attempt to create an ancient Roman "theme park" to glorify Fascist Italy. Several dozen buildings surrounding the Mausoleum were levelled to free up space around the monument. This led to a great number of complaints from locals, starting a long series of arguments and criticisms of the Ara Pacis project. These arguments are ongoing despite the original pavilion being replaced by a new one in 2006, known as the "Ara Pacis museum".


title: Ara Pacis

text: The historic Fascist style building around the Altar, locally known as "teca del Morpurgo", was pulled down in 2006, and replaced by a glass and steel structure in modern style, designed by architect Richard Meier. The new cover building, which has been named "Ara Pacis museum", now stands on the same site as Mussolini's structure. This new structure is much bigger than the previous one and it is divided into multiple rooms and sections besides the main one containing the altar.


title: Ara Pacis

text: Meier's building construction caused new arguments and criticism, after the ones which accompanied the first building construction, both from Roman inhabitants and foreign observers, probably due both to political memory tied to the pre-existing pavilion and to the visual impact of the new pavilion, which in the opinion of many is in stark contrast with surrounding historical buildings.


title: Ara Pacis

text: Nicolai Ouroussoff, of "The New York Times" called the building "a contemporary expression of what can happen when an architect fetishizes his own style out of a sense of self-aggrandizement. Absurdly over-scale, it seems indifferent to the naked beauty of the dense and richly textured city around it." Former mayor Gianni Alemanno, backed in July 2008 by culture undersecretary Francesco Maria Giro, pledged to tear down the new structure. He later changed his stance on the building and has agreed with Mr. Meier to modifications including drastically reducing the height of the wall between an open-air space outside the museum and a busy road along the Tiber river. The city plans to build a wide pedestrian area along the river and run the road underneath it. "It's an improvement," says Meier, adding that "the reason that wall was there has to do with traffic and noise. Once that is eliminated, the idea of opening the piazza to the river is a good one." The mayor's office said Alemanno hopes to complete the project before the end of his term in 2013.


title: Boy with Luv

text: "Boy with Luv" (Korean: 작은 것들을 위한 시; RR: "Jag-eun geosdeul-eul wihan si", "A Poem for Small Things") is a song recorded by South Korean boy band BTS, featuring American singer Halsey, as the lead single for their sixth extended play "". It was released on April 12, 2019, by Big Hit Entertainment. The song's music video was the most viewed online music video in 24 hours at the time, garnering over 74.6 million views within its first day of release. The song was certified Platinum by the RIAA in June. "Boy with Luv" held the record for the song with the most music show wins after the 2000s in South Korea with 21 wins, until the record was broken by "Dynamite".


title: Boy with Luv

text: On July 3, 2019, the Japanese version of the song was released as a double A-side single alongside an original Japanese track titled "Lights" via Universal Music Japan.


title: Boy with Luv

text: "Boy With Luv" featuring American singer Halsey has been described as a "funk pop" song about happiness and love. It serves as a parallel track to their earlier song "Boy in Luv", released in 2014. According to Tamar Herman of "Billboard", the song describes how true strength and love come from finding joy in the smallest things in life. Elias Leight from "Rolling Stone" classified the song as "nu-disco single". "NME" characterized it as "bubblegum pop". Yim Hyun-su from "The Korea Herald" described the lead single as "an upbeat electro-pop song with catchy hooks". According to "Refinery29", the light, funk-laced song features live instruments.


title: Boy with Luv

text: A trailer for the music video was released on April 7, 2019, with a 13-second clip of the song towards the end. The teaser features Halsey working in a ticket booth before walking outside to find BTS sitting on a couch. A second teaser, featuring close-ups of the band, was released on April 10.


title: Boy with Luv

text: Directed by Yong-Seok Choi from Lumpens, the full music video was released on April 12. It simultaneously obtained the records of fastest-liked video and fastest-viewed video on YouTube, reaching 3 million likes in 2 hours and 74.6 million views within 24 hours of release, making it the most viewed YouTube video in the first 24 hours after its release at the time, averaging about 860 views per second during that interval. It was also the fastest video to reach 100 million views on YouTube, doing so in approximately one day and 10 hours. On April 26, BigHit released a second version of the music video, titled "ARMY With Luv", dedicated to the band's fandom, ARMY. The video featured footage of the band not seen in the original version and more moments with Halsey; the large "LOVE" sign that appears atop a building while the band dances in the original was replaced with one that spelt "ARMY" instead. In December 2019, YouTube named it the most viewed music video in South Korea of the year. The music video crossed 1 billion views in October 2020, eighteen months after release, and is the band's second to reach the mark.


title: Boy with Luv

text: The band performed the song for the first time on April 13, 2019, as the musical guests on "Saturday Night Live" (making them the first K-Pop Group to perform on the show) and performed it with Halsey at the 2019 "Billboard" Music Awards held on May 1, 2019. BTS started their Korean promotion on April 18, 2019, on "M Countdown." They performed the song again to kick off "Good Morning America"s Summer Concert Series at New York's Central Park on May 15, 2019, along with their 2016 single, Fire. On May 16, 2019, BTS performed the song at "The Late Show with Stephen Colbert". On May 21, 2019, they performed the song at "The Voice"s finale. On May 30, 2019, they also performed the song at "Britain Got Talent"s semi-final.


title: Boy with Luv

text: On November 30, BTS performed "Boy with Luv" at the 2019 Melon Music Awards with throwbacks to "Boy in Luv". On December 4, the song was performed at the 2019 Mnet Asian Music Awards. Two days later, BTS performed the song at the KIIS-FM Jingle Ball in Los Angeles, where they appeared as a headliner. In addition, BTS performed the song in South Korea at the SBS Gayo Daejun and KBS Song Festival on December 25 and 27, respectively, following which the song was performed in New York's Times Square at "Dick Clark's New Year's Rockin' Eve".


title: Boy with Luv

text: Taylor Glasby writing for "Dazed" labelled "Boy With Luv" as "a beacon of pop sweetness". "Dazed" placed it in their list of "The 20 best K-pop songs of 2019" and commended the "catchy, made-for-radio immediacy" of the song, additionally characterizing "the playful lightness of the instrumental, vocals, and overall mood" that "bring to it a joyful ingenuousness and an old-world classiness that keeps the song sounding box fresh." Writing for the "Consequence of Sound", Laura Dzubay called the song "familiarly romantic". The song was included in "South China Morning Post"s list of "The 10 best K-pop songs of 2019". In that article, Jeff Benjamin described it as "euphoric pop sound" while praising how the song "shows their maturity and growth and comes with a message – to allow love to take over gradually and to make changes from the inside." Rhian Daly from "NME" called the song "addictive and deftly balanced" with Halsey's chorus "fitting in naturally and seamlessly"."Billboard" included the song in their list of "The 100 Best Songs of 2019: Staff List" as well as their list of "The 25 Best K-pop Songs of 2019: Critics' Picks". "NME" placed the song on their list of "The 50 best songs of 2019". It was also named as the Song of the Year through the public survey conducted by Gallup Korea in 2019.


title: Boy with Luv

text: Upon release, "Boy With Luv" debuted at No. 1 on the real-time charts of six major music sites including Soribada, Genie, Naver, Bugs, Mnet, and Flo on April 12. On the morning of April 13, it was reported that the song ranked No. 1 in real time charts of all digital platforms including Melon, thereby achieving an "all kill". In addition, all other tracks of "Map of the Soul: Persona" debuted in Top 10. It was reported that multiple servers crashed, including Korea's largest music site Melon, due to the number of fans streaming at the same time. "Boy With Luv" debuted at No. 1 on the Gaon Digital Chart and topped the weekly charts for three consecutive weeks. "Boy with Luv" debuted and peaked at No. 8 on the US "Billboard" Hot 100 Chart, becoming the group's highest Top 10 entry following "Fake Love". The song also debuted at No. 13 on the UK Official Singles Chart, making it the highest-charting single by a Korean act. The single also launched at No. 5 on the "Billboard" Streaming Songs chart, the highest rank for the band on the chart so far and the second top 10 after "Fake Love" peaked at No. 7, according to the Billboard website. It also ranked No. 3 on the Digital Song Sales chart, marking the group's fourth song hitting the chart's top 10.


title: Boy with Luv

text: "Boy with Luv" was certified Platinum by the Recording Industry Association of America (RIAA) in June, for selling over one million units in the United States. It is the group's second Platinum certification following "Mic Drop". The song surpassed 100 million streams on Gaon Music Chart, earning a Platinum certification from the Korea Music Content Association (KMCA). "Boy With Luv" was certified Gold by the Australian Recording Industry Association (ARIA) for selling 35,000 units in Australia.


title: Boy with Luv

text: BTS was named one of the Top 10 artists of 2019 by Genie Music with "Boy with Luv" topping their daily chart for 26 days.


title: Volkswagen Gol

text: The Volkswagen Gol is a subcompact car that has been manufactured by Volkswagen do Brasil since 1980 as Volkswagen's entry-level car in the Latin American market—where it succeeded the Volkswagen Type 1 (Fusca) and the VW Brasilia. Several variants of the Gol were marketed in North America as the Volkswagen Fox from 1987 to 1993.


title: Volkswagen Gol

text: The Gol has been produced in several versions, such as three- and five-door hatchbacks, four-door sedans (the Volkswagen Voyage), three- and five-door station wagons (the Volkswagen Parati), and two-door coupé utilities (the Volkswagen Saveiro).


title: Volkswagen Gol

text: The Gol was the best-selling car in Brazil for 27 consecutive years, from 1987 to 2014, and has been the most popular car in Argentina since 1988; approximately five million Gols have been manufactured in South America since 1980. In March 2013 it was announced that cumulative production of the Gol and its derivatives (Voyage, Saveiro, Parati) had reached 10 million units. It takes its name from the Portuguese word for goal in football, taking advantage of the Brazilians' passion for football.


title: Volkswagen Gol

text: The Gol family contains several body styles. The three- and five-door hatchback variants are known as the Volkswagen Gol in most markets, with the exception of Egypt and Russia, where they are marketed as the Volkswagen Pointer. The first-generation Gol was available only as a three-door hatchback; all generations since have offered a five-door variant as well.


title: Volkswagen Gol

text: The sedan has only been produced for the first and third (current) generations. The Brazilian-built sedans were marketed as the Volkswagen Voyage, while the Argentinian ones were referred to as the Volkswagen Gacel. In the United States and Canada, they were sold as the Volkswagen Fox. After a facelift in 1991, Argentinian-built models were renamed the Volkswagen Senda. In the second generation this model was replaced by the Volkswagen Polo Mk3 Classic, which was still sold in Mexico and Argentina. But a new Voyage notchback sedan returned in 2008 for the third generation.


title: Volkswagen Gol

text: Volkswagen Parati is a station wagon built on both generations since May 1982. The Parati I was a three-door sold in North America as the Fox Wagon. The second-generation Parati is sold in Argentina as the Gol Country. A five-door version was added in 1997 and the three-door version was dropped after the first facelift (G3). It is named after Paraty, a city on the southern coast of Rio de Janeiro state. It was formerly called Pointer Station Wagon in Mexico and it was sold there between 1999 and 2005. In 2013, The Parati was discontinued alongside the Gol G4 and was replaced by the SpaceFox.


title: Volkswagen Gol

text: Volkswagen Saveiro is a lightweight pickup truck. All Gol generations have been sold with this bodystyle, which was introduced to the market in 1983. It is named after a traditional Brazilian fishing boat. It is currently sold in Mexico since 1999 as the Pointer Pick Up.


title: Volkswagen Gol

text: The Gol was released in 1980 to replace the Brasilia, which was in turn a replacement for the Beetle on the Brazilian market. It was based on its own unique BX platform derived from the existing VW/Audi B1 and B2 platforms. With a design specific to Latin America, the Gol featured the 1.3-liter air-cooled, flat-four engine from the Beetle, but front-mounted. A 1.6-liter engine was added later. The Voyage two-door sedan variant of the Gol was released in June 1981 and received a 1.5-liter inline water-cooled gasoline engine instead. The same engine was offered with an ethanol option. In 1985, the air-cooled engine of the Gol was replaced by a 1.6-liter (and later 1.8-liter as well) longitudinally-mounted water-cooled gasoline inline-four engine from the Passat. By May 1982 the Voyage 1.5 was upgraded to 1.6. In 1984 a water-cooled Voyage 1.8 ("Super") was launched as a higher-level option. A 1.6-liter diesel engine was made, although only for export as diesel engines are not allowed in passenger cars in the Brazilian market.


title: Volkswagen Gol

text: In January 1983 a four-door Voyage sedan was released. It was known as the VW Amazon in some export markets, later as the Fox in North America. The four-door Voyage was built in the Autolatina Pacheco factory in Buenos Aires, Argentina from 1983 to 1994. It was sold under the name Gacel (later also as the Senda) with the Argentine-built 1.6 OHC engine with a carburettor, later also with a diesel 1.6.


title: Volkswagen Gol

text: The first generation (or "G1") Gol had two mild facelifts for 1987 and 1991. The 1989 Gol GTi was the first Brazilian-built car to use fuel injection. The 2.0-liter inline-four engine was the same used by the Santana. In 1991, as a result of changes to the tax laws in Brazil, a flurry of cars with engines under one liters appeared. Fiat was first (with the Fiat Mille), and Volkswagen quickly responded with the spartan Gol 1000. It had a Ford-developed 997 cc engine (a result of their recent Autolatina joint venture) with and was not available in any other bodystyle. Between 1990 and 1995 the Ford CHT 1.6 replaced the original 1.6 in the range, also as a result of the Autolatina lineup.


title: Volkswagen Gol

text: The Gol GT 1.8 was the BX family's first sports version and an answer to the Ford Escort XR3, a successful sports car in Brazilian market. With a 1.8 liter engine borrowed from Santana (MkII Passat), the Gol GT was much faster than the Escort XR3, but externally did not have the same beauty. The first series still had a four-speed manual gearbox, but soon this was changed to a five-speed unit.


title: Volkswagen Gol

text: Successor of Gol GT, the GTS had an updated design, following the new 87 BX line up style and also featuring new accessories that were not available before, such as rear spoiler and side skirts. The 1.8 liter engine produced running on gasoline or running on ethanol. The GTS was a very successful model and was kept in production alongside the upcoming GTI.


title: Volkswagen Gol

text: Known as the first Brazilian built car equipped with electronic fuel injection, the Gol GTI was presented in January 1989 and featured a larger 2.0 liter engine with power of running only on gasoline. Claimed top speed is . This engine was the same as used in the larger Santana, albeit fitted with fuel injection for the GTI.


title: Volkswagen Gol

text: Volkswagen Group of America marketed variants of the Gol (manufactured by Volkswagen do Brasil) in North America as entry level models from February 1987 until 1994 under the "Volkswagen Fox" nameplate. It was intended to provide Volkswagen dealers with a competitor to the then very successful Hyundai Excel and Yugo low-price cars. Initially offered as a two-door and four-door sedan as well as a two-door wagon, the wagon was discontinued for model year 1991 along with the two-door sedan for the Canadian market. That same year the remaining Fox versions received a mild restyling.


title: Volkswagen Gol

text: All North American models employed a longitudinally-mounted inline-four 1.8 L gasoline engine producing at 5,500 rpm and of torque at 3,250 rpm.


title: Volkswagen Gol

text: Early models (1987–1989) featured Bosch CIS-E type Jetronic electro-mechanical fuel injection, using an oxygen sensor to assist in fuel management. Later models (1990–1994) employed Bosch Digifant electronic fuel injection. In Canada from 1987–1989 it was offered with the simpler Bosch CIS fuel injection system without an oxygen sensor for the engine fuel management system.


title: Volkswagen Gol

text: Over the course of its model history, trim levels included base Fox, GL, GTS, GLS, GL Sport, Polo, and a Wolfsburg Edition. Options included air conditioning, five-speed (vs. four) manual transmission and metallic paint. No automatic transmission was offered. The GL trim featured revised cloth trim, rear license plate backing, ceiling-mounted map light, glove compartment light, trunk light, tachometer (excepting wagon models), body-colored bumpers, hubcaps, passenger side exterior rear view mirror, 175/70-13 tires, locking gas cap and three-point rear seat belts.


title: Volkswagen Gol

text: The 1991 facelift included revised grille, headlights, turn signals, badges, and hubcaps, as well as reduction of towing hooks from four to two. Later US models featured "automatic" non-motorized front seat shoulder belts along with a knee-bar and manual front lap belts, while the Canadian models have kept the manual pillar-mounted front seats.


title: Volkswagen Gol

text: The second generation (or "G2") Gol, known as "Project AB9" during development, debuted in September 1994. Still based on the BX platform, it was very different from the earlier model, with an updated body and longer wheelbase than the 1980 original. Nicknamed "Gol Bolinha" (roughly "Rounded Gol" or "Bubble Gol"), the previous generation started to be nicknamed as "Gol Quadrado", "Squared Gol". The new version was an answer to the then newly released Chevrolet Corsa.


title: Volkswagen Gol

text: The Gol G2 was available in the following versions: 1000i, 1000i Plus, CL, GL, Furgão (Wagon) and GTi (this one produced until 1996 with only a 8V engine, at which point a more powerful, German-built 16-valve version arrived), with 1.0, 1.6, 1.8, and 2.0 liter engines. The 1.0 was supplied by Ford, as part of the "AutoLatina" collaboration. The Gol G2 also had two special editions. The first, "Gol Rolling Stones", was in 1995 - commemorating that band's "Voodoo Lounge Tour" leg in Brazil. Then, the following year came "Gol Atlanta" (after the Olympic Games). In November 1996, Volkswagen began to produce its own 1.0 engine, called the AT-1000. This version was derived from their larger 1.6 (999 cc).


title: Volkswagen Gol

text: As the Ford-built engine had been in limited supply, Volkswagen could now ramp up production of their entry level Gols beginning in January 1997. There were also 16 valve versions of the 1.0 AT-1000 engine launched in September 1996. The 1.0 16V has , up from in the eight-valve version. In 1995 the Autolatina partnership was dissolved. In 1998, a 1.9 liter diesel engine was installed in the Gol G2, only sold in markets outside of Brazil.


title: Volkswagen Gol

text: Also this version of Gol had some chronic deficiencies of design, such as bad alignment of body parts, due to problems with the robots on the assembly line, and poor quality of plastic parts. A curious fact about this version of Gol is that the driver's seat is not well aligned with the steering wheel and pedals, causing a rather uncomfortable driving position. Another surprise was Volkswagen's original decision to sell the Gol and Parati (station wagon) only in three-door version, a step which was not appreciated by buyers. Fiat took the top spot in the Brazilian market for the last months of 1997, but once Volkswagen released quickly developed five-door models the Gol and Parati propelled Volkswagen back into first place in early 1998.


title: Volkswagen Gol

text: The first upgrade, in 1999 for 2000 model, was known as the Gol G3 (photo) in Brazil and had a new VW 'corporate' front end similar to the Jetta/Bora IV. The Gol G3 came with optional airbags and ABS brakes. The previous (G2) Gol 1.0 continued to be available as the "Gol Special", to fight for the lowest end of the market. Following the Mercosur economic crisis beginning with the Brazilian devaluation in 1999, the lineup was reduced in 2002. The 2.0 16V was discontinued, while the 1.8 was withdrawn from some markets. Argentinian production of the Gol was halted in 2003. Instead the engines at the bottom of the lineup were improved, with a 1.0 16V Turbo with a 1.0-liter turbocharged gasoline engine released in 2000.


title: Volkswagen Gol

text: When the 2005 (G4) Gol was released with styling cues from the Volkswagen Fox, incorporating the "V Grill", most avid automotive enthusiasts were unimpressed with the leap backwards in interior design. The G4 stayed in production until 2013, and was finally discontinued in 2015.


title: Volkswagen Gol

text: The flexible fuel vehicle Gol Total Flex, available since 2003, was the first of its kind in South America. Its introduction followed a rehabilitation of the use of alcohol to power automobiles.


title: Volkswagen Gol

text: The Gol G2 was introduced in Mexico in spring 1998 as the Volkswagen Pointer (a name previously used in Latin America for a rebadged model based on the Ford Escort Mk V, the Pointer/Logus). The only version for this year was a three-door hatchback with a 1.8 liter, engine and a five-speed manual gearbox. The only extra cost option available was a package compounding air conditioning and power steering. For 1999, a five-door wagon version, the Brazilian Parati (called the Pointer Station Wagon in Mexico) and the Saveiro (called the Pointer Pick Up) are added. They were marketed in three trim levels: Base, Comfort (A/C and power steering) and Luxe (14" alloy wheels, power windows and remote control centralized door locks, A/C and power steering). For 2000 the Pointer received the same facelift as in Brazil and a sporty Pointer GTI based on the Brazilian Gol GTI is introduced. It was a three-door hatchback with a 2.0 liter, engine. It had AM/FM/Cassette radio, alloy wheels, all around disc brakes, and sporty black seats as standard equipment. In 2002 a basic Pointer City version is introduced, the former Comfort version is renamed the Trendline, and the Luxe variant as the Comfortline. In 2005 the Pointer Station Wagon and the Pointer GTI are discontinued and the former Pointer trims (but the City) are replaced by a new Pointer Mi version.


title: Volkswagen Gol

text: In the model year 2007, the Pointer receives the newest facelift, and its versions are reorganized. The Pointer is currently marketed as the Base, A/C (Air Conditioning, power steering and rear wiper/washer), Trendline (Radio AM/FM Stereo CD, 15" alloy wheels, fog lamps), and GT (only available as a five-door hatchback. It has the same equipment as the Trendline plus: rear headrests, 6 spoke 15" alloy wheels, black accented headlamps, rear spoiler, and sport seats). The Pointer was replaced in December 2008 by the new Volkswagen Gol G5 which has been launched in Brazil in July 2008.


title: Volkswagen Gol

text: The Gol G3 was briefly sold in Russia in 2004-2006 as the Pointer, but the sales were soon discontinued due to low demand. The car was available with the 1.0-liter () and the 1.8-liter () engines.


title: Volkswagen Gol

text: The third generation of the Gol was released in Brazil, on 29 June 2008, as a 2009 model. Referred to before its launch as the "Gol NF" for "Nachfolger" or "Neue Familie" (German terms for "successor" and "new family" respectively), this model is marketed as the "Novo Gol". However, it is no longer based on the BX platform, but shares Volkswagen's PQ24 platform with the Fox and Polo, with some components from the PQ25 platform.


title: Volkswagen Gol

text: In Brazil, it was released in three and five-door hatchback version with the options of 1.0-liter or 1.6-liter flex engines. Its dimensions are 3.90 m in length, 1.66 m in width, 1.45 m in height with a wheelbase of 2.47 m, and luggage capacity of 285 liters. It is the first Gol to be offered with an automated manual transmission.


title: Volkswagen Gol

text: The advertisements were filmed in Los Angeles, California, featuring Sylvester Stallone and Gisele Bündchen.


title: Volkswagen Gol

text: Volkswagen High Torque (VHT) technology was introduced on the third generation Gol family. This new technology allows the flex engine to get the high torques at lower revs, the engines produce higher torques and horsepower on Ethanol fuel.


title: Volkswagen Gol

text: Revealed in September 2008, the Voyage is the sedan variant of the current Gol and as such has the same running gear 1.0 and 1.6 liter VHT ethanol compatible engines. In several countries, the Voyage is called the Gol Sedan.


title: Volkswagen Gol

text: The Voyage is available in four versions on the Brazilian market; 1.0, 1.6, 1.6 Trend, and 1.6 Comfortline, all with standard with ABS brakes and dual front airbags.


title: Volkswagen Gol

text: The Voyage's trunk can be electronically operated via a button on the dash or by pressing the keypad; the luggage capacity is 480 liters.


title: Volkswagen Gol

text: Production of the sedan bodystyle ended in Brazil in 1995 and resumed in 2008, so although this is only the second generation of the Voyage, it is called the G5 in line with the equivalent Gol hatchback.


title: Volkswagen Gol

text: In August 2009, VW Brazil revealed the third generation Saveiro utility. The new Saveiro is available with a standard cabin or an extended cabin, sharing the same wheelbase which is longer than that of the Gol and Voyage. The only available engine, the 1.6L VHT, carries over from the Gol and Voyage.


title: Volkswagen Gol

text: The most basic 1.6 specification has black bumpers and 14-inch steel wheels. The optional Trend package includes 14-inch alloy wheels and color-coded door handle and mirror covers; the top of the line is the Saveiro Trooper which has black-painted 15-inch steel wheels.


title: Volkswagen Gol

text: The third generation of the Gol received a facelift in 2012, with more angular headlights and taillights, similar to the sixth-generation Volkswagen Jetta.


title: Volkswagen Gol

text: The model received another facelift in 2016, based on the fifth-generation Volkswagen Polo and the seventh-generation Volkswagen Golf. A new 1.0 liter three-cylinder was introduced, the same engine used on the Brazilian-specification Up! and Fox models, with the option of ethanol or gasoline, or a combination of both. The Rallye version based on the CrossFox with a 16-valve 1.6 liter four-cylinder was discontinued, leaving only the 8-valve 1.6 liter engine as an option to the 1.0 liter engine. The interior received a new dashboard and steering wheel similar to the Golf, with the option of a multimedia center with the navigation system, Android Auto and Apple CarPlay and MirrorLink.


title: Volkswagen Gol

text: The Gol has been rated as highly unsafe by Latin NCAP, the 2009 model in its most basic Latin American configuration with no airbags scoring only one star for adult occupants and two stars for children. Its airbag-equipped version scored three stars. No ESP is offered, but since 2014, Brazilian law requires ABS brakes and dual front airbags in all new vehicles.


title: Volkswagen Gol

text: Since January 2022, the Gol is banned from sale in Argentina following the entry into force of the law prohibiting the sale of new vehicles not equipped with ESP. Volkswagen has been very critical of the new law to make this active safety equipment mandatory. By refusing to equip the Gol with ESP, Volkswagen had to stop marketing the model in Argentina, even though it was the third best-selling passenger car on the local market in 2021.


title: Volkswagen Gol

text: Production of the Gol ended in late 2022. A Last Edition model for the 2023 model year with exterior upgraded was released in Brazil, with production limited to 1,000 units. It will be replaced with a less equipped version of the Polo Mk6, which was introduced as the Polo Track in November 2022.


title: Biscuits and gravy

text: Biscuits and gravy is a popular breakfast dish in the United States, especially in the South. The dish consists of soft dough biscuits covered in white gravy (sawmill gravy), made from the drippings of cooked pork sausage, flour, milk, and often (but not always) bits of sausage, bacon, ground beef, or other meat. The gravy is often flavored with black pepper.


title: Biscuits and gravy

text: The meal emerged as a distinct regional dish after the American Revolutionary War (1775–1783), when stocks of foodstuffs were in short supply. Breakfast was necessarily the most substantial meal of the day for a person facing a day of work on the plantations in the American South. In addition, the lack of supplies and money meant it had to be cheap.


title: Biscuits and gravy

text: Restaurant chains specializing in biscuits and gravy include Biscuitville, in Virginia and North Carolina, and Tudor's Biscuit World, in West Virginia.


title: Tribology

text: Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. People who work in the field of tribology are referred to as "tribologists".


title: Tribology

text: The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. In lubricated tribosystems, contact stress can create tribofilms. Subfields of tribology include biotribology, nanotribology, space tribology and tribotronics.


title: Tribology

text: The word "tribology" derives from the Greek root τριβ- of the verb , "tribo", "I rub" in classic Greek, and the suffix "-logy" from , "-logia" "study of", "knowledge of". Peter Jost coined the word in 1966, in the eponymous report which highlighted the cost of friction, wear and corrosion to the UK economy.


title: Tribology

text: Despite the relatively recent naming of the field of tribology, quantitative studies of friction can be traced as far back as 1493, when Leonardo da Vinci first noted the two fundamental 'laws' of friction. According to Leonardo, frictional resistance was the same for two different objects of the same weight but making contact over different widths and lengths. He also observed that the force needed to overcome friction doubles as weight doubles. However, Leonardo's findings remained unpublished in his notebooks.


title: Tribology

text: The two fundamental 'laws' of friction were first published (in 1699) by Guillaume Amontons, with whose name they are now usually associated. They state that:


title: Tribology

text: Although not universally applicable, these simple statements hold for a surprisingly wide range of systems. These laws were further developed by Charles-Augustin de Coulomb (in 1785), who noticed that static friction force may depend on the contact time and sliding (kinetic) friction may depend on sliding velocity, normal force and contact area.


title: Tribology

text: In 1798, Charles Hatchett and Henry Cavendish carried out the first reliable test on frictional wear. In a study commissioned by the Privy Council of the UK, they used a simple reciprocating machine to evaluate the wear rate of gold coins. They found that coins with grit between them wore at a faster rate compared to self-mated coins. In 1860, Theodor Reye proposed . In 1953, John Frederick Archard developed the Archard equation which describes sliding wear and is based on the theory of asperity contact.


title: Tribology

text: Other pioneers of tribology research are Australian physicist Frank Philip Bowden and British physicist David Tabor, both of the Cavendish Laboratory at Cambridge University. Together they wrote the seminal textbook "The Friction and Lubrication of Solids" (Part I originally published in 1950 and Part II in 1964). Michael J. Neale was another leader in the field during the mid-to-late 1900s. He specialized in solving problems in machine design by applying his knowledge of tribology. Neale was respected as an educator with a gift for integrating theoretical work with his own practical experience to produce easy-to-understand design guides. "The Tribology Handbook", which he first edited in 1973 and updated in 1995, is still used around the world and forms the basis of numerous training courses for engineering designers.


title: Tribology

text: Duncan Dowson surveyed the history of tribology in his 1997 book "History of Tribology" (2nd edition). This covers developments from prehistory, through early civilizations (Mesopotamia, ancient Egypt) and highlights the key developments up to the end of the twentieth century.


title: Tribology

text: The term "tribology" became widely used following "The Jost Report" published in 1966. The report highlighted the huge cost of friction, wear and corrosion to the UK economy (1.1–1.4% of GDP). As a result, the UK government established several national centres to address tribological problems. Since then the term has diffused into the international community, with many specialists now identifying as "tribologists".


title: Tribology

text: Despite considerable research since the Jost Report, the global impact of friction and wear on energy consumption, economic expenditure, and carbon dioxide emissions are still considerable. In 2017, Kenneth Holmberg and Ali Erdemir attempted to quantify their impact worldwide. They considered the four main energy consuming sectors: transport, manufacturing, power generation, and residential. The following were concluded:


title: Tribology

text: Classical tribology covering such applications as ball bearings, gear drives, clutches, brakes, etc. was developed in the context of mechanical engineering. But in the last decades tribology expanded to qualitatively new fields of applications, in particular micro- and nanotechnology as well as biology and medicine.


title: Tribology

text: The word friction comes from the Latin "frictionem", which means rubbing. This term is used to describe all those dissipative phenomena, capable of producing heat and of opposing the relative motion between two surfaces. There are two main types of friction:


title: Tribology

text: The study of friction phenomena is a predominantly empirical study and does not allow to reach precise results, but only to useful approximate conclusions. This inability to obtain a definite result is due to the extreme complexity of the phenomenon. If it is studied more closely it presents new elements, which, in turn, make the global description even more complex.


title: Tribology

text: All the theories and studies on friction can be simplified into three main laws, which are valid in most cases:


title: Tribology

text: Consider a block of a certain mass m, placed in a quiet position on a horizontal plane. If you want to move the block, an external force formula_1 must be applied, in this way we observe a certain resistance to the motion given by a force equal to and opposite to the applied force, which is precisely the static frictional force formula_2.


title: Tribology

text: By continuously increasing the applied force, we obtain a value such that the block starts instantly to move. At this point, also taking into account the first two friction laws stated above, it is possible to define the static friction force as a force equal in modulus to the minimum force required to cause the motion of the block, and the coefficient of static friction formula_3 as the ratio of the static friction force formula_2. and the normal force at block formula_5, obtaining


title: Tribology

text: Once the block has been put into motion, a friction force, with a lesser intensity than of the one of static friction formula_2, which is the dynamic friction force formula_8.In this case it is necessary to take into account not only the first two laws of Amontons, but also of the law of Coulomb, so as to be able to affirm that the relationship between dynamic friction force formula_8, coefficient of dynamic friction "k" and normal force "N" is the following:


title: Tribology

text: At this point it is possible to summarize the main properties of the static friction coefficients formula_3 and the dynamic one formula_12.


title: Tribology

text: These coefficients are dimensionless quantities, given by the ratio between the intensity of the friction force formula_13and the intensity of the applied load formula_14, depending on the type of surfaces that are involved in a mutual contact, and in any case, the condition is always valid such that: formula_15.


title: Tribology

text: Usually, the value of both coefficients does not exceed the unit and can be considered constant only within certain ranges of forces and velocities, outside of which there are extreme conditions that modify these coefficients and variables.


title: Tribology

text: The following table shows the values of the static and dynamic friction coefficients for common materials:


title: Tribology

text: In the case of bodies capable of rolling, there is a particular type of friction, in which the sliding phenomenon, typical of dynamic friction, does not occur, but there is also a force that opposes the motion, which also excludes the case of static friction. This type of friction is called rolling friction. Now we want to observe in detail what happens to a wheel that rolls on a horizontal plane. Initially the wheel is immobile and the forces acting on it are the weight force formula_16 and the normal force formula_17given by the response to the weight of the floor.


title: Tribology

text: At this point the wheel is set in motion, causing a displacement at the point of application of the normal force which is now applied in front of the center of the wheel, at a distance "b", which is equal to the value of the rolling friction coefficient. The opposition to the motion is caused by the separation of the normal force and the weight force at the exact moment in which the rolling starts, so the value of the torque given by the rolling friction force is


title: Tribology

text: What happens in detail at the microscopic level between the wheel and the supporting surface is described in Figure, where it is possible to observe what is the behavior of the reaction forces of the deformed plane acting on an immobile wheel.


title: Tribology

text: Rolling the wheel continuously causes imperceptible deformations of the plane and, once passed to a subsequent point, the plane returns to its initial state. In the compression phase the plane opposes the motion of the wheel, while in the decompression phase it provides a positive contribution to the motion.


title: Tribology

text: The force of rolling friction depends, therefore, on the small deformations suffered by the supporting surface and by the wheel itself, and can be expressed as formula_19, where it is possible to express "b" in relation to the sliding friction coefficient formula_3 as formula_21, with "r" being the wheel radius.


title: Tribology

text: Going even deeper, it is possible to study not only the most external surface of the metal, but also the immediately more internal states, linked to the history of the metal, its composition and the manufacturing processes undergone by the latter.


title: Tribology

text: The layer of oxides and impurities (third body) has a fundamental tribological importance, in fact it usually contributes to reducing friction. Another fact of fundamental importance regarding oxides is that if you could clean and smooth the surface in order to obtain a pure "metal surface", what we would observe is the union of the two surfaces in contact. In fact, in the absence of thin layers of contaminants, the atoms of the metal in question, are not able to distinguish one body from another, thus going to form a single body if put in contact.


title: Tribology

text: Contact between surfaces is made up of a large number of microscopic regions, in the literature called asperities or junctions of contact, where atom-to-atom contact takes place. The phenomenon of friction, and therefore of the dissipation of energy, is due precisely to the deformations that such regions undergo due to the load and relative movement. Plastic, elastic, or rupture deformations can be observed:


title: Tribology

text: The energy that is dissipated during the phenomenon is transformed into heat, thus increasing the temperature of the surfaces in contact. The increase in temperature also depends on the relative speed and the roughness of the material, it can be so high as to even lead to the fusion of the materials involved.


title: Tribology

text: In friction phenomena, temperature is fundamental in many areas of application. For example, a rise in temperature may result in a sharp reduction of the friction coefficient, and consequently, the effectiveness of the brakes.


title: Tribology

text: The adhesion theory states that in the case of spherical asperities in contact with each other, subjected to a formula_14 load, a deformation is observed, which, as the load increases, passes from an elastic to a plastic deformation. This phenomenon involves an enlargement of the real contact area formula_23, which for this reason can be expressed as:


title: Tribology

text: where D is the hardness of the material definable as the applied load divided by the area of the contact surface.


title: Tribology

text: If at this point the two surfaces are sliding between them, a resistance to shear stress "t" is observed, given by the presence of adhesive bonds, which were created precisely because of the plastic deformations, and therefore the frictional force will be given by


title: Tribology

text: At this point, since the coefficient of friction is the ratio between the intensity of the frictional force and that of the applied load, it is possible to state that


title: Tribology

text: thus relating to the two material properties: shear strength "t" and hardness. To obtain low value friction coefficients formula_3 it is possible to resort to materials which require less shear stress, but which are also very hard. In the case of lubricants, in fact, we use a substrate of material with low cutting stress "t", placed on a very hard material.


title: Tribology

text: The force acting between two solids in contact will not only have normal components, as implied so far, but will also have tangential components. This further complicates the description of the interactions between roughness, because due to this tangential component plastic deformation comes with a lower load than when ignoring this component. A more realistic description then of the area of each single junction that is created is given by


title: Tribology

text: To obtain even more realistic considerations, the phenomenon of the third body should also be considered, i.e., the presence of foreign materials, such as moisture, oxides or lubricants, between the two solids in contact. A coefficient c is then introduced which is able to correlate the shear strength "t" of the pure "material" and that of the third body formula_31


title: Tribology

text: By studying the behavior at the limits it will be that for "c" = 0, "t" = 0 and for "c" = 1 it returns to the condition in which the surfaces are directly in contact and there is no presence of a third body. Keeping in mind what has just been said, it is possible to correct the friction coefficient formula as follows:


title: Tribology

text: where, in this case, "K" depends on the elastic properties of the materials. Also for the elastic bodies the tangential force depends on the coefficient "c" seen above, and it will be


title: Tribology

text: The simplest and most immediate method for evaluating the friction coefficient of two surfaces is the use of an inclined plane on which a block of material is made to slide. As can be seen in the figure, the normal force of the plane is given by formula_37, while the frictional force is equal to formula_38. This allows us to state that the coefficient of friction can be calculated very easily, by means of the tangent of the angle in which the block begins to slip. In fact we have


title: Tribology

text: Then from the inclined plane we moved on to more sophisticated systems, which allow us to consider all the possible environmental conditions in which the measurement is made, such as the cross-roller machine or the pin and disk machine. Today there are digital machines such as the "Friction Tester" which allows, by means of a software support, to insert all the desired variables. Another widely used process is the ring compression test. A flat ring of the material to be studied is plastically deformed by means of a press, if the deformation is an expansion in both the inner and the outer circle, then there will be low or zero friction coefficients. Otherwise for a deformation that expands only in the inner circle there will be increasing friction coefficients.


title: Tribology

text: To reduce friction between surfaces and keep wear under control, materials called lubricants are used. Unlike what you might think, these are not just oils or fats, but any fluid material that is characterized by viscosity, such as air and water. Of course, some lubricants are more suitable than others, depending on the type of use they are intended for: air and water, for example, are readily available, but the former can only be used under limited load and speed conditions, while the second can contribute to the wear of materials.


title: Tribology

text: What we try to achieve by means of these materials is a perfect fluid lubrication, or a lubrication such that it is possible to avoid direct contact between the surfaces in question, inserting a lubricant film between them. To do this there are two possibilities, depending on the type of application, the costs to address and the level of "perfection" of the lubrication desired to be achieved, there is a choice between:


title: Tribology

text: The viscosity is the equivalent of friction in fluids, it describes, in fact, the ability of fluids to resist the forces that cause a change in shape.


title: Tribology

text: Thanks to Newton's studies, a deeper understanding of the phenomenon has been achieved. He, in fact, introduced the concept of laminar flow: "a flow in which the velocity changes from layer to layer". It is possible to ideally divide a fluid between two surfaces (formula_40, formula_41) of area A, in various layers.


title: Tribology

text: The layer in contact with the surface formula_41, which moves with a velocity "v" due to an applied force "F", will have the same velocity as "v" of the slab, while each immediately following layer will vary this velocity of a quantity "dv", up to the layer in contact with the immobile surface formula_40, which will have zero speed.


title: Tribology

text: From what has been said, it is possible to state that the force "F", necessary to cause a rolling motion in a fluid contained between two plates, is proportional to the area of the two surfaces and to the speed gradient:


title: Tribology

text: At this point we can introduce a proportional constant formula_3, which corresponds to the dynamic viscosity coefficient of the fluid, to obtain the following equation, known as Newton's law


title: Tribology

text: The speed varies by the same amount "dv" of layer in layer and then the condition occurs so that "dv" / "dy" = "v" / "L", where "L" is the distance between the surfaces formula_40 and formula_41, and then we can simplify the equation by writing


title: Tribology

text: The viscosity formula_3 is high in fluids that strongly oppose the motion, while it is contained for fluids that flow easily.


title: Tribology

text: This is a constant that depends on the fluid mass formula_52 of the fluid, on its viscosity formula_3 and on the diameter "L" of the tube in which the fluid flows. If the Reynolds number is relatively low then there is a laminar flow, whereas for formula_54 the flow becomes turbulent.


title: Tribology

text: To conclude we want to underline that it is possible to divide the fluids into two types according to their viscosity:


title: Tribology

text: Temperature and pressure are two fundamental factors to evaluate when choosing a lubricant instead of another. Consider the effects of temperature initially.


title: Tribology

text: In order to classify the various lubricants according to their viscosity behavior as a function of temperature, in 1929 the viscosity index (V.I.) was introduced by Dean and Davis. These assigned the best lubricant then available, namely the oil of Pennsylvania, the viscosity index 100, and at the worst, the American oil of the Gulf Coast, the value 0. To determine the value of the intermediate oil index, the following procedure is used: two reference oils are chosen so that the oil in question has the same viscosity at 100 °C, and the following equation is used to determine the viscosity index


title: Tribology

text: In the case of oils with V.I. above 100 you can use a different relationship that allows you to get exact results


title: Tribology

text: where, in this case, H is the viscosity at of the oil with V.I. = 100 and v is the kinematic viscosity of the study oil at .


title: Tribology

text: We can therefore say, in conclusion, that an increase in temperature leads to a decrease in the viscosity of the oil. It is also useful to keep in mind that, in the same way, an increase in pressure implies an increase in viscosity. To evaluate the effects of pressure on viscosity, the following equation is used


title: Tribology

text: where formula_59 is the pressure viscosity coefficient p, formula_60 is the viscosity coefficient at atmospheric pressure and formula_61 is a constant that describes the relationship between viscosity and pressure.


title: Tribology

text: To determine the viscosity of a fluid, viscosimeters are used which can be divided into 3 main categories:


title: Tribology

text: The first two types of viscometers are mainly used for Newtonian fluids, while the third is very versatile.


title: Tribology

text: The wear is the progressive involuntary removal of material from a surface in relative motion with another or with a fluid. We can distinguish two different types of wear: moderate wear and severe wear. The first case concerns low loads and smooth surfaces, while the second concerns significantly higher loads and compatible and rough surfaces, in which the wear processes are much more violent. Wear plays a fundamental role in tribological studies, since it causes changes in the shape of the components used in the construction of machinery (for example). These worn parts must be replaced and this entails both a problem of an economic nature, due to the cost of replacement, and a functional problem, since if these components are not replaced in time, more serious damage could occur to the machine in its complex. This phenomenon, however, has not only negative sides, indeed, it is often used to reduce the roughness of some materials, eliminating the asperities. Erroneously we tend to imagine wear in a direct correlation with friction, in reality these two phenomena can not be easily connected. There may be conditions such that low friction can result in significant wear and vice versa. In order for this phenomenon to occur, certain implementation times are required, which may change depending on some variables, such as load, speed, lubrication and environmental conditions, and there are different wear mechanisms, which may occur simultaneously or even combined with each other:


title: Tribology

text: As known, the contact between two surfaces occurs through the interaction between asperities. If a shearing force is applied in the contact area, it may be possible to detach a small part of the weaker material, due to its adhesion to the harder surface. What is described is precisely the mechanism of the adhesive wear represented in the figure. This type of wear is very problematic, since it involves high wear speeds, but at the same time it is possible to reduce adhesion by increasing surface roughness and hardness of the surfaces involved, or by inserting layers of contaminants such as oxygen, oxides, water, or oils. In conclusion, the behavior of the adhesive wear volume can be described by means of three main laws


title: Tribology

text: An important aspect of wear is emission of wear particles into the environment which increasingly threatens human health and ecology. The first researcher who investigated this topic was Ernest Rabinowicz.


title: Tribology

text: The abrasive wear consists of the cutting effort of hard surfaces that act on softer surfaces and can be caused either by the roughness that as tips cut off the material against which they rub (two-body abrasive wear), or from particles of hard material that interpose between two surfaces in relative motion (three-body abrasive wear). At application levels, the two-body wear is easily eliminated by means of an adequate surface finish, while the three-body wear can bring serious problems and must therefore be removed as much as possible by means of suitable filters, even before of a weighted machine design.


title: Tribology

text: The fatigue wear is a type of wear that is caused by alternative loads, which cause local contact forces repeated over time, which in turn lead to deterioration of the materials involved. The most immediate example of this type of wear is that of a comb. If you slide a finger over the teeth of the comb over and over again, it is observed that at some point one or more teeth of the comb come off. This phenomenon can lead to the breaking of the surfaces due to mechanical or thermal causes. The first case is that described above in which a repeated load causes high contact stresses. The second case, however, is caused by the thermal expansion of the materials involved in the process. To reduce this type of wear, therefore, it is good to try to decrease both the contact forces and the thermal cycling, that is the frequency with which different temperatures intervene. For optimal results it is also good to eliminate, as much as possible, impurities between surfaces, local defects and inclusions of foreign materials in the bodies involved.


title: Tribology

text: The corrosive wear occurs in the presence of metals that oxidize or corrode. When the pure metal surfaces come into contact with the surrounding environment, oxide films are created on their surfaces because of the contaminants present in the environment itself, such as water, oxygen or acids. These films are continually removed from the abrasive and adhesive wear mechanisms, continually recreated by pure-contaminating metal interactions. Clearly this type of wear can be reduced by trying to create an 'ad hoc' environment, free of pollutants and sensible to minimal thermal changes. Corrosive wear can also be positive in some applications. In fact, the oxides that are created, contribute to decrease the coefficient of friction between the surfaces, or, being in many cases harder than the metal to which they belong, can be used as excellent abrasives.


title: Tribology

text: The rubbing wear occurs in systems subject to more or less intense vibrations, which cause relative movements between the surfaces in contact within the order of nanometers. These microscopic relative movements cause both adhesive wear, caused by the displacement itself, and abrasive wear, caused by the particles produced in the adhesive phase, which remain trapped between the surfaces. This type of wear can be accelerated by the presence of corrosive substances and the increase in temperature.


title: Tribology

text: The erosion wear occurs when free particles, which can be either solid or liquid, hit a surface, causing abrasion. The mechanisms involved are of various kinds and depend on certain parameters, such as the impact angle, the particle size, the impact velocity and the material of which the particles are made up.


title: Tribology

text: It has been verified that the harder a material is, the more it decreases. In the same way, the less two materials are mutually soluble, the more the wear tends to decrease. Finally, as regards the crystalline structure, it is possible to state that some structures are more suitable to resist the wear of others, such as a hexagonal structure with a compact distribution, which can only deform by slipping along the base planes.


title: Tribology

text: To provide an assessment of the damage caused by wear, we use a dimensionless coefficient called wear rate, given by the ratio between the height change of the body formula_62 and the length of the relative sliding formula_63.


title: Tribology

text: This coefficient makes it possible to subdivide, depending on its size, the damage suffered by various materials in different situations, passing from a modest degree of wear, through a medium, to a degree of severe wear.


title: Tribology

text: where W / H represents the real contact area, l the length of the distance traveled and k and formula_67 are experimental dimensional factors.


title: Tribology

text: In experimental measurements of material wear, it is often necessary to recreate fairly small wear rates and to accelerate times. The phenomena, which in reality develop after years, in the laboratory must occur after a few days. A first evaluation of the wear processes is a visual inspection of the superficial profile of the body in the study, including a comparison before and after the occurrence of the wear phenomenon. In this first analysis the possible variations of the hardness and of the superficial geometry of the material are observed. Another method of investigation is that of the radioactive tracer, used to evaluate wear at macroscopic levels. One of the two materials in contact, involved in a wear process, is marked with a radioactive tracer. In this way, the particles of this material, which will be removed, will be easily visible and accessible. Finally, to accelerate wear times, one of the best-known techniques used is that of the high pressure contact tests. In this case, to obtain the desired results it is sufficient to apply the load on a very reduced contact area.


title: Tribology

text: Historically, tribology research concentrated on the design and effective lubrication of machine components, particularly for bearings. However, the study of tribology extends into most aspects of modern technology and any system where one material slides over another can be affected by complex tribological interactions.


title: Tribology

text: Traditionally, tribology research in the transport industry focused on reliability, ensuring the safe, continuous operation of machine components. Nowadays, due to an increased focus on energy consumption, efficiency has become increasingly important and thus lubricants have become progressively more complex and sophisticated in order to achieve this. Tribology also plays an important role in manufacturing. For example, in metal-forming operations, friction increases tool wear and the power required to work a piece. This results in increased costs due to more frequent tool replacement, loss of tolerance as tool dimensions shift, and greater forces required to shape a piece.


title: Tribology

text: The use of lubricants which minimize direct surface contact reduces tool wear and power requirements. It is also necessary to know the effects of manufacturing, all manufacturing methods leave a unique system fingerprint (i.e. surface topography) which will influence the tribocontact (e.g. lubricant film formation).


title: Tribology

text: Tribology research ranges from macro to nano scales, in areas as diverse as the movement of continental plates and glaciers to the locomotion of animals and insects. Tribology research is traditionally concentrated on transport and manufacturing sectors, but this has considerably diversified. Tribology research can be loosely divided into the following fields (with some overlap):


title: Tribology

text: Recently, intensive studies of superlubricity (phenomenon of vanishing friction) have sparked due to increasing demand for energy savings. Furthermore, the development of new materials, such as graphene and ionic liquids, allows for fundamentally new approaches to solve tribological problems.


title: Tribology

text: There are now numerous national and international societies, including: the Society of Tribologists and Lubrication Engineers (STLE) in the US, the Institution of Mechanical Engineers and Institute of Physics (IMechE Tribology Group, IOP Tribology Group) in the UK, the German Society for Tribology (Gesellschaft für Tribologie), the Korean Tribology Society (KTS), the Malaysian Tribology Society (MYTRIBOS), the Japanese Society of Tribologists (JAST), the Tribology Society of India (TSI), the Chinese Mechanical Engineering Society (Chinese Tribology Institute) and the International Tribology Council.


title: Tribology

text: Tribology research is mostly empirical, which can be explained by the vast number of parameters that influence friction and wear in tribological contacts. Thus, most research fields rely heavily on the use of standardized tribometers and test procedures as well component-level test rigs.


title: Tribology

text: The concept of tribosystems is used to provide a detailed assessment of relevant inputs, outputs and losses to tribological systems. Knowledge of these parameters allows tribologists to devise test procedures for tribological systems.


title: Tribology

text: Tribofilms are thin films that form on tribologically stressed surfaces. They play an important role in reducing friction and wear in tribological systems.


title: Tribology

text: The Stribeck curve shows how friction in fluid-lubricated contacts is a non-linear function of lubricant viscosity, entrainment velocity and contact load.


title: Washer (hardware)

text: A washer is a thin plate (typically disk-shaped, but sometimes square) with a hole (typically in the middle) that is normally used to distribute the load of a threaded fastener, such as a bolt or nut. Other uses are as a spacer, spring (Belleville washer, wave washer), wear pad, preload indicating device, locking device, and to reduce vibration (rubber washer).


title: Washer (hardware)

text: Washers are usually metal or plastic. High-quality bolted joints require hardened steel washers to prevent the loss of pre-load due to brinelling after the torque is applied. Washers are also important for preventing galvanic corrosion, particularly by insulating steel screws from aluminium surfaces. They may also be used in rotating applications, as a bearing. A "thrust washer" is used when a rolling element bearing is not needed either from a cost-performance perspective or due to space restraints. Coatings can be used to reduce wear and friction, either by hardening the surface or by providing a solid lubricant (i.e. a self-lubricating surface).


title: Washer (hardware)

text: The origin of the word is unknown; the first recorded use of the word was in 1346, however, the first time its definition was recorded was in 1611.


title: Washer (hardware)

text: Rubber or fiber gaskets used in taps (or faucets, or valves) as seal against water leaks are sometimes referred to colloquially as "washers"; but, while they may look similar, washers and gaskets are usually designed for different functions and made differently.


title: Washer (hardware)

text: Lock washers, locknuts, jam nuts, and thread-locking fluid are ways to prevent vibration from loosening a bolted joint.


title: Washer (hardware)

text: The term washer is often applied to various gasket types such as those used to seal the control valve in taps.


title: Washer (hardware)

text: The DIN 125 metric washer standard refers to subtypes A and B. ISO 7089 calls these Form A and ISO 7090 calls them Form B. They are all the same overall size, but Form B is chamfered on one side.


title: Washer (hardware)

text: A number of techniques are used to enhance the corrosion resistant properties of certain washer materials:


title: Washer (hardware)

text: The American National Standards Institute (ANSI) provides standards for general use flat washers. Type A is a series of steel washers at broad tolerances, where precision is not critical. Type B is a series of flat washers with tighter tolerances where outside diameters are categorized as "narrow", "regular" or "wide" for specific bolt sizes.


title: Washer (hardware)

text: "Type" is not to be confused with "form" (but often is). The British Standard for Metric Series Metal Washers (BS4320), written in 1968, coined the term "form". The forms go from A to G and dictate the outside diameter and thickness of the flat washers.


title: Washer (hardware)

text: Washers of standard metric sizes equivalent to BS4320 Form A are listed in the table below. Measurements in the table refer to the dimensions of the washers as described by the drawing. Specifications for standard metric flat washers were known as DIN 125 (withdrawn) and replaced with ISO 7089. DIN (Deutsches Institut für Normung - German Institute for Standardization) standards are issued for a variety of components including industrial fasteners as Metric DIN 125 Flat Washers. The DIN standards remain common in Germany, Europe and globally even though the transition to ISO standards is taking place. DIN standards continue to be used for parts which do not have ISO equivalents or for which there is no need for standardization.


title: President of Bolivia

text: The president of Bolivia (), officially known as the president of the Plurinational State of Bolivia (), is head of state and head of government of Bolivia and the captain general of the Armed Forces of Bolivia.


title: President of Bolivia

text: According to the Bolivian Constitution, the president is elected by popular vote to a five-year term with no limit on the number of terms a president may serve. If no candidate wins a majority (defined as either more than 50%, or alternatively at least 40% and at least 10% more than the second-place candidate), the top two candidates advance to a runoff election.


title: President of Bolivia

text: On 6 August 1825, the Republic of Bolivia declared its independence and proclaimed Simón Bolívar head of state. While it is certainly true that Bolívar was the official ruler of the country starting from his arrival on 12 August, there exists conflict amongst scholars as to whether he should be considered the first president of the republic. According to the research of the Bolivian historian Isaac Sandoval, in his book ""Political development in the social formation of Bolivia"" it is affirmed that the first president of Bolivia was not Bolívar, but Antonio José de Sucre. This is due to the fact that Bolívar is never referred to as president in legal documents and was never sworn-in having renounced the title in favor of Sucre on 29 December 1825. Sucre, on the other hand, was president when the country's first Constitution was promulgated on 19 November 1826.


title: President of Bolivia

text: Historian and author of the book ""Presidents of Bolivia: Between urns and rifles"" Carlos Mesa asserts that Bolívar was indeed the first president and that the lack of mention of him with the title is due to the fact the term "president" was not in common use in legal documents at the time. Mesa points to the Congressional decree of 11 August 1825 which proclaims Bolívar "liberator" granting him "Supreme Executive Power of the Republic." Whatever the case, the position of Simón Bolívar as the first president is the most generally accepted stance.


title: President of Bolivia

text: The Political Constitution of 1826, also known as the Bolivarian Constitution, was the first constitutional text prepared by Simón Bolívar, sanctioned by the General Constituent Congress on 6 November 1826 and promulgated by Antonio José de Sucre on 19 November 1826. In this first instance, the presidency constituted a lifetime position with the power to elect and appoint a successor. The lifetime position was repealed during the presidency of Andrés de Santa Cruz who promulgated the Political Constitution of 1831. Instead, the president would serve for a four-year term of government with the ability to be reelected unlimitedly.


title: President of Bolivia

text: The 2009 Political Constitution, approved by referendum on 25 January 2009 and promulgated by President Evo Morales on 7 February resulted in the official name of the country, leaving behind its previous denominative of "Republic of Bolivia" to become "the Plurinational State of Bolivia". As such, Evo Morales became was the 65th and last President of the Republic and the first President of the State. The Constitution extended the term of the president from four years to five years while keeping the two-term limit. On 21 February 2016, a proposal to abolish term limits failed to pass via constitutional referendum by a margin of 51% to 49%. Despite this, on 28 November 2017, the Supreme Tribunal of Justice ruled that all elected officials could run for office indefinitely, rather than for the two consecutive terms permitted under the 2009 Constitution. The court justified its decision based on the American Convention on Human Rights' interpretation of political rights.


title: President of Bolivia

text: Prior to 2009, if no candidate won more than half of the popular vote, the president was chosen by a vote in a joint legislative session from among the top two candidates (prior to 1995, the top three). This system led to multiple times in which the loser of the popular vote, once even the third place finisher, were elected president. This was replaced by a two-round system in which if no party won more than half of the popular vote in the first electoral round, the top two contenders would run in a runoff election.


title: President of Bolivia

text: Of the 67 people who have served as President of Bolivia, 13 (19%) died by tragic means, five died in office, and three died by assassination; Pedro Blanco Soto was shot while trying to escape custody, Agustín Morales was shot in self-defense after he attacked one of his military assistants, and Gualberto Villarroel was lynched outside the government palace. Germán Busch committed suicide and René Barrientos died in a helicopter crash, both deaths are rumored to have been planned assassinations. A further eight former presidents were assassinated in various ways after leaving office.


title: President of Bolivia

text: According to Article 169 I of the 2009 Constitution: "In the event of an impediment or definitive absence of the president, he or she shall be replaced by the vice president and, in the absence of the latter, by the president of the Senate, and in his or her absence by the president of the Chamber of Deputies. In this last case, new elections shall be called within a maximum period of 90 days.


title: President of Bolivia

text: Historically there have been multiple periods of time during different constitutions in which the office of vice president has been rendered nonexistent and more still in which the office was vacant. Between 26 October 1839 and 15 February 1878, the office of vice president was abolished with the president of the Senate being the first in the line of succession. During this time, Eusebio Guilarte and Tomás Frías Ametller both came to power in their capacity as President of the Council of State.


title: President of Bolivia

text: Rather than complete the previous president's term, interim presidents have held office until new elections could be held even if that period of time runs past or cuts short the previous president's term. José María Pérez de Urdininea, Felipe Segundo Guzmán, Carlos Blanco Galindo, Carlos Quintanilla, Néstor Guillén, Tomás Monje, Wálter Guevara, Lidia Gueiler Tejada, Eduardo Rodríguez and most recently Jeanine Áñez all came to power as interim presidents due to the fact the previous president had resigned, been deposed, died, or otherwise left office and new elections had to be held to elect a valid successor.


title: President of Bolivia

text: José Miguel de Velasco Franco was initially the acting president in the absence of Andrés de Santa Cruz but became interim president due to the fact Santa Cruz never arrived to be sworn-in, forcing a new president to have to be elected by Congress.


title: President of Bolivia

text: In the case of temporary incapacity or absence from the country, the title of Acting President () is transferred to lower officials according to the order of presidential succession. In September 2012, Senate president Gabriela Montaño became the first woman to assume this office, during the presidency of Evo Morales. José Miguel de Velasco Franco, Mariano Enrique Calvo, and Pedro José Domingo de Guerra were acting presidents for particularly long periods of time of multiple months or, in the case of Enrique Calvo, multiple years.


title: President of Bolivia

text: The Palacio Quemado, in English "Burnt Palace," in the legal capital of La Paz was the official residence of the president of Bolivia from 1853 to 2018. Its nickname originates from the fact that it was set aflame and burned almost to the ground when rebels in opposition to Tomás Frías Ametller failed to storm it and instead opted to light it on fire in 1875. It has since been rebuilt and redecorated a number of times, but the name stuck. At the end of 2018, it ceased to function as the headquarters of the government offices, with plans to turn it instead into a museum. Briefly occupied again from 2019 to 2020, it has since returned to being a museum.


title: President of Bolivia

text: In 2018, the official residence of the president was moved by President Evo Morales to the Casa Grande del Pueblo, known in English as the "Great House of the People", replacing the Palacio Quemado as the seat of the Executive Branch of the Plurinational State of Bolivia. Inaugurated on 9 August 2018, the building houses the president as well as various government ministries. In 2019, Interim President Jeanine Áñez refused to use the new building and returned operations to the Palacio Quemado, though the ministries and other government offices continued to operate within the new building. The Casa Grande returned to being the residence of the president upon the inauguration of Luis Arce on 8 November 2020.


title: President of Bolivia

text: The transportation of the president of Bolivia is the charge of the Bolivian Presidential Air Group, for the transportation of the president at the national short-range level the EC145 helicopter is used, for national and international transportation the Falcon 900EX EASY aircraft is used, both manufactured by Dassault Aviation (France) that make up part of the Bolivian Air Force's aircraft.


title: President of Bolivia

text: The Presidential Bodyguard is made up of the 1st Bolivian Colorados infantry regiment, which is a military unit of the Bolivian Army whose specific mission is to protect the security and physical integrity of the president of Bolivia and whose charge is the custody of the Palace of Government and the Casa Grande, as well as other properties of the presidency.


title: President of Bolivia

text: It has two infantry battalions, the BI-201 and BI-202, with their respective barracks, both located in the city of La Paz. The "Calama headquarters" is located on the street on the same name where the unit's headquarters and the regimental barracks and training depot operate and the Mirador barracks with a seat on the Quilli Quilli hill. The Villa Pavón area is a training center in various areas of specialization such as assault, support, protection of people, first aid, etc. There are also bedrooms in the Casa Grande del Pueblo for the soldiers who watch and stand guard at the government palace at night.


title: President of Bolivia

text: Since its independence in 1825, Bolivia has been ruled by key figures in the fight for independence, leaders of the War of the Pacific, representatives of the aristocracy, military dictators and democratically elected leaders. Due to the complexities in the rise to power of these individuals, in Bolivia presidents are divided between two groups. The first are what are classified as "Constitucionales" having come to power legally or through quasi-legal means (achieving power through a revolution or coup d'état but later constitutionalised). The rest are known as de facto presidents, having come to power militarily and never constitutionalised. A third category belongs to interim presidents, placed in power only until a new president is chosen. Interim presidents have historically been both constitutional or de facto depending on the legality of their rise to the office.


title: President of Bolivia

text: Throughout Bolivian history, there have been six periods of time in 1839, 1841, 1848, 1879–1880, and most recently in 2019 in which there has been no head of state. Seven governments were made up of triumvirates: , 1899, , 1970, 1978, 1981, and 1982. For one month in 1928, Hernando Siles Reyes' cabinet ruled the country being the only time when a constituted government was not presided over by an agent. In 1965, faced with discontent from loyalists of Alfredo Ovando Candía, President René Barrientos established the co-presidency between himself and Ovando on 26 May 1965. This is the only example of two presidents ruling at once in Bolivian history and it lasted until 2 January 1966 when Barrientos resigned to run for president in the upcoming general elections.


title: President of Bolivia

text: In 1983, a poll was taken by "Última Hora" newspaper to determine which seven historical presidents were regarded as most significant. The "winners" were Antonio José de Sucre, Andrés de Santa Cruz, Manuel Isidoro Belzu, Mariano Melgarejo, Aniceto Arce, Ismael Montes, and Víctor Paz Estenssoro.