cahya/simple-wikipedia huggingface dataset:
Electromagnetic waves are waves that contain an electric field and a magnetic field and carry energy. They travel at the speed of light.

Quantum mechanics developed from the study of electromagnetic waves. This field includes the study of both visible and invisible light. Visible light is the light one can see with normal eyesight in the colours of the rainbow. Invisible light is light one can't see with normal eyesight and includes more energetic and higher frequency waves, such as ultraviolet, x-rays and gamma rays. Waves with longer lengths, such as infrared, micro and radio waves, are also explored in the field of Quantum mechanics.

Some types of electromagnetic radiation, such as X-rays, are ionizing radiation and can be harmful to your body. 
Ultraviolet rays are near the violet end of the light spectrum and infrared are near the red end.  Infrared rays are heat rays and ultraviolet rays cause sunburn.

The various parts of the electromagnetic spectrum differ in wavelength, frequency and quantum energy.

Sound waves are not electromagnetic waves but waves of pressure in air, water or any other substance.

Mathematical formulation
In physics, it is well known that the wave equation for a typical wave is

The problem now is to prove that Maxwell's equations explicitly prove that the electric and magnetic fields create electromagnetic radiation. Recall that two of Maxwell's equations are given by

By  evaluating the curl of the above equations and vector calculus one can prove the following equations

Note: the proof involves making the substitution

The equations above are analogous to the wave equation, by replacing f with E and B. The above equations mean that propagations through the magnetic (B) and electric (E) fields will produce waves.

Related pages 
 Photon

References

Other websites
 Electromagnetic Waves from Maxwell's Equations   on Project PHYSNET.
Conversion of frequency to wavelength and back - electromagnetic, radio and sound waves
eBooks on Electromagnetic radiation and RF
The Science of Spectroscopy  - supported by NASA. Spectroscopy education wiki and films - introduction to light, its uses in NASA, space science, astronomy, medicine & health, environmental research, and consumer products.

 
Electromagnetism
The Miami Dolphins is an American football club in the National Football League team based in Miami, Florida, USA. The Dolphins began playing in 1966 and in 1972 they had the only perfect season in NFL history and won a Super Bowl, with Bob Griese leading the team as quarterback. Another quarterback, Dan Marino, is a more recent famous player from this club.  The Miami Dolphins stadium is Hard Rock Stadium in Miami Gardens, Fl.

References

Sports in Miami, Florida
National Football League teams
1966 establishments in the United States
1960s establishments in Florida
Oksana Vladimirovna Grishuk (born March 17, 1972 in Odessa, Ukraine) is a Russian retired ice dancer. She and her partner, Evgeny Platov, won two Olympic gold medals and four world championships.

Grishuk began training in skating at the age of four. She moved to Moscow in 1986, and studied at the Sport University from 1988 to 1992.

After they won the gold medal in the 1998 Winter Olympics in Nagano, Japan, Platov decided to skate as a professional with a different partner, Maya Usova, so Grishuk began skating professionally alone.

Amateur competitions
World Championships:  first in 1994, 1995, 1996, and 1997
Olympics:  gold medal in 1994 and 1998
European Championships:  first place in 1996, 1997, and 1998

References

Other websites

 The largest fansite about Oksana Grishuk, AKA Pasha  
 Oksana Grishuk's official website 
 Platov and Usova site

1972 births
Living people
Olympic gold medalists
People from Odessa
Russian figure skaters
Evgeny Platov (born August 7, 1967, Odessa, Ukraine).

He was a Russian dancer, and began skating when he was nine years old.  He studied at the Physical Institute of Culture in Moscow.  

Platov won two Olympic gold medals and four world championships with his partner, Oksana Grishuk 

After the 1998 Olympics in Nagano, Japan, Platov started skating as a professional with a different partner, Maya Usova, until he retired from performing in 2002.  He is now a coach at Princeton Sports Center in Princeton, New Jersey.

Amateur competitions
World Championships:  first in 1994, 1995, 1996, and 1997
Olympics:  gold medal in 1994 and 1998
European Championships:  first place in 1996, 1997, and 1998

References

Other websites

 Platov and Usova site

1972 births
Living people
Olympic gold medalists
Russian figure skaters
A tetris is a tile-matching puzzle game, developed in the Soviet Union in 1984. The game has a simple goal of destroying lines of block before it reaches the top. The line is made up of a square block. etrominoes is the shape of the 4 connected blocks that falls vertically down. The player will have to use the tetrominos to create lines that fill the box horizontally, this will clear the lines of blocks. The game continues, the lines of blocks that is not completely filled will drop down as many lines that were cleared. The game has levels of difficulties which rises as the game is being played.

Tetris has appeared in many video game system. It has become very common from back when Alexey Pajitnov first made it in 1984. With over 170 million copies sold, it is the 2nd best-selling video game of all time.

Gameplay

The goal is to drop blocks, called tetrominoes, down into a playing field to make lines. Tetriminoes are made of four connected squares each  There are seven different types of tetrominoes. Levels have a set goal, or number of lines to clear. When the goal number reaches zero, the player moves to the next level. As the levels go up, the tetrominoes fall faster. A player receives bonus points if he can clear more than one line with a single tetromino. Clearing four lines is called a "tetris", three lines a "triple" and two lines a "double". Clearing two tetrises in a row is called a back-to-back tetris. The player can also turn a T-shaped tetromino into a hole, called a T-slot, to get more points. This move is called a "T-spin". A player loses when the tetrominoes make it to the top of the playing field. See "Issues" for information on the Level 29 Problem.

Music
On the Game Boy, there are several musical themes played. The theme for level 1 and used in the Game Boy version is often called the "Tetris Theme". It is actually a Russian dance called Korobeiniki, or "The Peddlers." Other themes include music by Johann Sebastian Bach and the Dance of the Sugar Plum Fairy.

Issues
When you reach Level 28 on the GBA(Game Boy Advance) or NES(Nintendo Entertainment System), the pieces will start falling so fast that the player can hardly move the tetrominoes at all. This means that those pieces will all pile up on the playfield and cause the player to lose.

References

1984 video games
Moldova is a country in Eastern Europe. Its full name is the Republic of Moldova (, .) It used to be called Moldavia. It borders Ukraine to the north and Romania to the south.

The official language in Moldova is the Romanian language. The capital of Moldova is Chișinău.

The Russian Empire took almost half of the Principality of Moldova in 1812 and called it Bessarabia.  Between 1918 - 1940 and 1941-1944 it was part of the Kingdom of Romania. It became independent from the Soviet Union after its dissolution. 

The average monthly salary/wages are still low, standing at only $243 USD.  Moldova is an associated country for future membership in the European Union.

Related pages
 List of rivers of Moldova
 Moldova at the Olympics
 Moldova national football team

References
Georgia could mean either of two things:
Georgia (country), a country in the Caucasus
Georgia (U.S. state), one of the states in the United States of America

Related pages
Georgian, a disambiguation page
Kryptos is the name of a sculpture (art that is like a statue) on the grounds of the Central Intelligence Agency (CIA) in Langley, Virginia, USA.  Kryptos is very famous.  It has codes (secret hidden messages) on it.  There are four messages.  People know what three of the messages say.  No one knows what the fourth message says yet.

A man named Jim Sanborn made Kryptos in 1990.  Kryptos is in a garden in the middle of a building called CIA Headquarters.  

Not very many people have seen Kryptos, because only a few people are allowed to go into the CIA building.  They do very important work at the CIA, and have to be very careful.

The word Kryptos comes from the Greek language.  It means "hidden".

The sculpture is about 12 feet high and 20 feet long.  It is made of metal and different kinds of rocks. It has thousands of letters and other things written in the metal. 

The first person to find out what the first three messages say, was Jim Gillogly.  He learned the answers in 1999.  After he said what the answer was, the CIA said that a man who works at the CIA, David Stein, knew the answer too.  A few years later the NSA (another agency in Washington D.C.) said that they had people who had solved it too.

Before he made Kryptos, Jim Sanborn had not made any other sculptures with letters on them.  After Kryptos he made many other sculptures with letters on them.  Some of them have secret messages. One is called Antipodes.  There are two copies of Antipodes.  One belongs to a man in California.  The other is in a museum in Washington DC called the Hirshhorn Museum.  

Another sculpture that Sanborn made which has secret messages is called the Cyrillic Projector.  It has secret messages in Russian.  The Cyrillic Projector was independently cracked by Michael Bales and Frank Corr in 2003.

There are two famous books that talk about Kryptos, which were written by Dan Brown. He wrote a book in 2003 called The Da Vinci Code.  On the cover of the book is art.  In the art there are secret messages.  Two of the messages talk about Kryptos.  Dan Brown wrote another book in 2009 called The Lost Symbol, which also talks about Kryptos.

Other websites
The CIA website about Kryptos 
NY Times Library An article in the newspaper (The New York Times: CIA's Artistic Enigma Reveals All but Final Clues, – June 16, 1999)
Elonka Dunin's Kryptos page
Washington Post ("Cracking the Code of a CIA Sculpture" – July 19, 1999)
New York Times article and other articles  ("Gillogly Cracks CIA Art", & "The Kryptos Code Unmasked")
Wired News ("Solving the Enigma of Kryptos" – January 21, 2005)
CNN story, "Cracking the Code", June 19, 2005

Pictures of Kryptos from high up in the sky
Windows Live Local - Several images. (zoom in and click on aerial / bird's eye links at left)
Terraserver-USA
Google Maps

Sculptures
Virginia
Lech Walesa (Polish: Lech Wałęsa (pronounced [lɛx vaˈwɛ̃sa])) (born September 29, 1943) was a Polish shipyard worker, trade unionist and a politician who used to be the leader of Solidarity and the President of Poland between 1990 and 1995. Walesa won the Nobel Peace Prize in 1983.

References

1943 births
Living people
Knights Grand Cross of the Order of the Bath
Nonviolence advocates
Order of Merit of the Federal Republic of Germany
Polish Nobel Prize winners
Polish Roman Catholics
Presidents of Poland
Time People of the Year
Trade unionists
These are some Dutch football (soccer) teams.

Eredivisie (Honour Division)
Season 2018/19
 ADO Den Haag
 Ajax
 AZ Alkmaar
 Emmen
 SBV Excelsior
 Feyenoord Rotterdam
 Fortuna Sittard
 De Graafschap
 FC Groningen
 SC Heerenveen
 Heracles Almelo
 NAC Breda
 PEC Zwolle
 PSV Eindhoven
 FC Utrecht
 Vitesse
 VVV-Venlo
 Willem II

Eerste Divisie (First Division)
 Almere City FC
 Cambuur Leeuwarden
 FC Den Bosch
 FC Dordrecht
 FC Eindhoven
 Excelsior
 Fortuna Sittard
 Go Ahead Eagles
 De Graafschap
 Helmond Sport
 MVV
 FC Oss
 Sparta Rotterdam
 Telstar
 BV Veendam
 FC Volendam

Lists of football teams
General Charles André Joseph Marie de Gaulle (22 November 1890 - 9 November 1970) was a French military and political leader. He was president of France from 1959 to 1969. He was a founding member and leader of the French Resistance during the Second World War. He died of an aneurysm.

De Gaulle chaired the Provisional Government of the French Republic from 1944 to 1946 in order to re-establish democracy in France.

In 1958, he came out of retirement: the Algerian War was happening. He rewrote the Constitution of France and founded the Fifth Republic after it was by a referendum. He was elected President of France later that year, a position to which he was re-elected in 1965 and held until his resignation in 1969.

The National Assembly brought him back to power in May 1958. He granted independence to Algeria. 900,000 French people in Algeria (called les pieds-noire) left for France. The Organisation armée secrète (OAS) tried to kill him. Frederick Forsyth used this incident as a basis for his novel The Day of the Jackal.

After the Algerian conflict, de Gaulle wanted to improve the French economy, and have an independent foreign policy. This was called by foreign observers the "politics of grandeur" (politique de grandeur). See Gaullism.

The French economy recorded high growth rates. In 1964, for the first time in nearly 100 years, France's GDP overtook that of the United Kingdom. This period is still remembered in France with some nostalgia as the peak of the Trente Glorieuses ("Thirty Glorious Years" of economic growth between 1945 and 1974).

De Gaulle had many admirers, but he was also one of the most hated men in modern French history.

His most famous saying was: "L'etat? c'est moi!", roughly "The State? it's me!"

References 

1890 births
1970 deaths
Cardiovascular disease deaths in France
Deaths from aneurysm
French generals
French people of World War II
Prime Ministers of France
People from Lille
Presidents of France
Time People of the Year
The Sumatran tiger (Panthera tigris sumatrae) is the smallest tiger subspecies. It is listed as critically endangered. They are in danger due to hunting and the destruction of their habitat. It is estimated that there are only about 400-700 Sumatran tigers left in the wild.

The Sumatran tiger lives only on the Indonesian island of Sumatra. It can be found in low and highland areas, mountainous jungles, and peat swamp forests.

Description

Like other tiger subspecies, the Sumatran tiger has deep orange fur with black stripes. Every tiger has its own pattern of stripes, with none being the same. The Sumatran tiger has very long back legs, which allow it to jump great distances. Even though they are the smallest of the tiger subspecies, Sumatran tigers are still very large, reaching to the length of 9 feet (2.7 meters), and weighing up to 165-250 pounds (75–114 kg). Sumatran tigers have webbed feet. This allows them to swim easily.

Where they live 

The Sumatran tiger is found only on the Indonesian island of Sumatra, where the Sumatran tiger can be found from low and highland areas, to mountainous jungles and peat swamp forests.

Feeding
Sumatran tigers ambush their prey, using their long, powerful legs, jaws, and claws to catch and kill their prey. They have extremely good eyesight and hearing, which helps them to find their prey. Sumatran tigers feed mainly on wild boar and deer, and they can eat more than 40 pounds of meat at a time.

Reproduction
Female Sumatran tigers reach maturity at the age of around three to four years. Males turn mature at the age of around four to five years. Females are pregnant for about 95–110 days, and the females give birth in hidden and private areas and raise the cubs alone. They give birth to around 2-3 cubs at a time, but they can sometimes give birth to six cubs. The cubs’ eyes are closed at birth, and they don’t open fully until the cub is one or two weeks old. Cubs feed on milk for three to six months and start hunting with their mother at the age of about five or six months. They will stay with their mother until they are fully able to hunt on their own, which doesn’t happen until the cubs are at least 18 months to 2 years old. In the wild, Sumatran tigers live an average of 15 years.

References

Other websites

The Sumatran Tiger Trust 
Tiger Facts - Sumatran Tiger

Tigers
Indonesia
The American Film Institute (AFI) is an independent, organization that is designed not to make money created by the National Endowment for the Arts, which was started in 1967 when President Lyndon B. Johnson signed the National Foundation on the Arts and the Humanities Act.

George Stevens, Jr. was the first CEO. Since 1980, Jean Picker Firstenberg has been CEO.

Older figures in AFI's Conservatory train newer people.

The institute also wants to keep old film, which could soon be destroyed.

Even though its name only mentions film, AFI also works on television and video.

In 1973, the AFI began handing out Life Achievement Awards.

In 1998, when American cinema had existed for 100 years, AFI began its 100 Years Series, which helped people become interested in the history of movies.

Recently, it built and started the AFI Silver theatre in Silver Spring, Maryland near Washington, D.C.

AFI 100 Years series
In honour of the hundredth birthday of American cinema, the AFI has made several lists of the best movie-related things:

 1998: AFI's 100 Years... 100 Movies
 1999: AFI's 100 Years... 100 Stars
 2000: AFI's 100 Years... 100 Laughs
 2001: AFI's 100 Years... 100 Thrills
 2002: AFI's 100 Years... 100 Passions
 2003: AFI's 100 Years... 100 Heroes and Villains
 2004: AFI's 100 Years... 100 Songs
 2005: AFI's 100 Years... 100 Movie Quotes
 2005: AFI's 100 Years of Film Scores
 2006: AFI's 100 Years... 100 Cheers

References

Other websites 
 Official Website
 History of AFI
 AFI Los Angeles Film Festival - History and Information 

 
1967 establishments in California
8 Mile is a 2002 American drama movie starring rapper Eminem, Kim Basinger, Brittany Murphy and Mekhi Phifer. It is set in 1995 in Detroit, Michigan.

The film tells about a young white rapper living in inner city Detroit. He tries to make a rap career but most rappers are African Americans.

The film was a critical and financial success. Eminem won the Academy Award for Best Original Song for "Lose Yourself".

Other websites

References

2002 drama movies
American drama movies
American musical movies
Eminem
English-language movies
Movies set in Detroit, Michigan
Movies set in the 1990s
Movies that won the Best Original Song Academy Award
Universal Pictures movies
Movies directed by Curtis Hanson
Events 
Beginning of the Napoleonic Wars (1803–1815). 
Semaphore is adopted by navies. 
The United Kingdom was founded (1801)

World leaders 
 Emperor Napoleon I (First French Empire)
 Emperor Francis II (Holy Roman Empire)
 Frederick William III of Prussia (Prussia)
 Pope Pius VII
 Tsar Paul I (Russia)
 Tsar Alexander I (Russia)
 King Charles IV (Spain)
 King George III, (United Kingdom)
 President John Adams (United States)
 President Thomas Jefferson (United States)
 Fath Ali Shah of Qajar dynasty (Persia)
 Jiaqing Emperor of China (Qing Dynasty)
A convertible is a car with a roof that can be removed or folded down, but is often seen without a roof. A convertible usually has two doors, but convertibles with four doors can also be found. Some examples are Mazda MX-5, BMW Z4, Ferrari 458 Spyder, Mercedes-Benz SLK Class, etc. A convertible is a type of automobile of various automobile body styles that can convert from open-air (top-down or topless) mode to a provisionally enclosed (roofed or top-up) mode. Convertibles evolved from the earlier Phaeton, a similar vehicle without glass side windows that may or may not have had removable panels of fabric or other material instead to protect passengers from rain and cold, etc. A semi-convertible or cabrio coach is similar to a convertible and also has a retractable or removable top, but has fully framed windows on its side doors as opposed to a convertible's roll-down frameless windows that provide an even more open car driving experience.

Roof designs have varied widely and have evolved from the earliest models, where roofs were demountable and/or detachable. Contemporary roofs are often hinged to fold away, either into a recess behind the rear seats or into the boot or trunk of the vehicle. The roof may operate either manually or automatically via hydraulic or electrical actuators, and the roof itself may be constructed of soft or rigid material. Soft-tops are made of vinyl, canvas or other textile material, while hard-tops are made of steel, aluminum, plastic, or other rigid materials.

The majority of convertible cars are two door models, with markedly fewer four-door models.

Convertibles may also be referred to as cabriolet, roadster, tourer or drophead coupé and the colloquial terms drop top and rag top are also used. Hard-top convertibles may be called coupé cabriolet, coupé convertible, retractable hardtop or, when equipped with two seats, coupé roadster/roadster coupé.

Other websites

Automobile body styles
Macy Gray (born Natalie Renee McIntyre on September 9, 1967) is an American singer and actress. She started her career after moving to Los Angeles in 2000. Gray is best known for her 1999 single, "I Try", which came off of her first album, On How Life Is.

Discography

Albums
1999: On How Life Is
2001: The Id
2003: The Trouble with Being Myself
2004: The Very Best of Macy Gray
2005: Live in Las Vegas
2007: Big
2010: The Sellout
2012: Covered
2012: Talking Book

References

Other websites 

Actors from Ohio
African American actors
African American musicians
American movie actors
American R&B singers
American soul musicians
American television actors
American voice actors
Brit Award winners
Grammy Award winners
People from Canton, Ohio
Singers from Ohio
1967 births
Living people
Citizen Kane is a 1941 American drama movie starring Orson Welles in his first full-length movie. There are rumors that its story is based on the life of the famous businessmen William Randolph Hearst, Howard Hughes, and Samuel Insull. Welles said that his character, Kane, was based on more than one famous person. In F for Fake (1974), he said that Kane was going to be based on Hughes but that Welles became inspired by Hearst.

Welles worked closely with his cinematographer, Gregg Toland, who was in charge of the camera and the lights. Together, they worked on a new style, "deep focus." Usually, if something close to the camera is in focus, everything that is far away is out of focus. In deep focus, every object is in focus at the same time.

Its working title, before the movie was finished, was RKO 281.

Many have called Citizen Kane the best movie of all time. In 1998, it was number one on the American Film Institute's list of 100 Years... 100 Movies.

It is in some ways is like The Power and the Glory (1933).

The last living crew member was director Robert Wise. Also known for making The Sound of Music (1965), he died on September 14, 2005.

Other websites 

 
 The American Film Institute's "100 Greatest Movies" list 
 Original Trailer 
 Greatest Films: Citizen Kane
 Essay  on the use of mise-en-scene and cinematography
 RaveCentral: Citizen Kane 

1941 movies
1940s drama movies
American drama movies
American mystery movies
Cult movies
Movies composed by Bernard Herrmann
United States National Film Registry movies
Movies directed by Orson Welles
Dynamite is an explosive invented by Alfred Nobel. Its main explosive component is nitroglycerin. Nitroglycerin is very sensitive to movement. It explodes very easily, when moved. For this reason, it is absorbed into diatomaceous earth to make it less sensitive. Diatomaceous earth is a soft, sedimentary rock made of fossil diatoms. In dynamite, about one part of four is diatomaceous earth, the other three are nitroglycerin. A little sodium carbonate is added to stabilize the mixture. 

Even though the diatomaceous earth takes away some of the dangers of nitroglycerin, there are still problems because the mixture is not stable in damp environments. Water causes the nitroglycerin to leak away. The nitroglycerin can build up, and explode unexpectedly. 

For this reason, the formulation was changed. Instead of diatomaceous earth, gelignite was used to hold the nitroglycerin. Gelignite holds the nitroglycerin so that it cannot dissolve in water. 

Today, dynamite is not much used. It has been replaced by explosives based on ammonium nitrate which use gelignite. These explosives cost less to make and are easier to handle than dynamite. However, works of fiction still show people using dynamite.

Explosives
Tools
Construction
Demolition
Guano is the excrement of bats and birds. This excrement is exceptionally high in nitrogen, phosphate, and potassium, three nutrients which are essential for plant growth. Therefore, it is often used as fertilizer, to make plants grow more quickly.

Related pages 
 Uric acid

Physiology
Biochemistry
Events 

 French Revolution
 Supreme Court of the United States meets for first time.
 Whiskey Rebellion in the United States.

World leaders 
 King Louis XVI (France)
 Maximilien Robespierre (France)
 King George III (Great Britain)
 Emperor Leopold II (Holy Roman Empire)
 Emperor Francis II (Holy Roman Empire)
 Frederick William II of Prussia, King of Prussia
 Emperor Kangxi (China)
 Pope Pius VI
 Empress Catherine II (Russia)
 Emperor Paul (Russia)
 King Charles IV (Spain)
 President George Washington (United States)
 President John Adams (United States)
 Shahs of Persia (Zand dynasty and Qajar dynasty)
 Lotf Ali Khan, 1789–1794
 Agha Mohammad Khan Qajar, 1796–1797
 Fath Ali Shah, 1797–1834

Births 

 Jean-François Champollion, French Egyptologist (1790)
 Samuel Morse, American inventor (1791)
 Antonio López de Santa Anna, Mexican general and President of Mexico (1794)

Deaths 

 Benjamin Franklin, American scientist and statesman (1790)
 Wolfgang Amadeus Mozart, Austrian composer (1791)
 George Washington, first President of the United States (1799)
The triple point of any substance is the combination of temperature and pressure at which it exists in its solid, liquid, and gaseous state all at once, in equilibrium.

The temperature of the triple point of water is a commonly used physical constant which is used to define temperature scales and calibrate temperature-measuring systems.

By definition, the temperature of the triple point of water is 273.16 Kelvin, or 0.01°C at a pressure of 611.5 Pa (less than 1% of atmospheric pressure). One degree Celsius is defined as 1/273.16th part of the triple point of water. This fixes the temperature scale as defined in the ITS 90, which is the international temperature scale of 1990. This scale is developed as a practical approximation of the thermodynamical temperature scale.

Chemistry
Thermodynamics
Frequency is how often an event repeats itself over a set amount of time.

In physics, the frequency of a wave is the number of wave crests that pass a point in one second (a wave crest is the peak of the wave).

Hertz (symbol Hz) is the unit of frequency.

The relationship between frequency and wavelength is expressed by the formula: 

where v is speed and  (lambda) is wavelength. The formula for the frequency of light waves is  where the c is the speed of light.

All electromagnetic waves travel at the speed of light in a vacuum but they travel at slower speeds when they travel through a medium that is not a vacuum. Other waves, such as sound waves, travel at much much lower speeds and can not travel through a vacuum.

Examples of electromagnetic waves are: light waves, radio waves, infrared radiation, microwaves, and gamma waves.

Visualizing electromagnetic waves 
Different types of electromagnetic waves have different frequencies.

Example 

One way to visualize this is if there were two trains traveling at the same speed, but the size of the train cars was smaller on one train than the other. If someone picked something that was not moving, like a signpost, and then counted how many train cars passed the sign post in one second for each train, they would know the frequency of cars passing in each train. The number and frequency of train cars passing the sign post would be different, because the train with smaller train cars would have more train cars passing the sign post in a second than the train with larger train cars. Knowing how many cars passed the sign post in one second, and knowing the speed of the train, one could figure out mathematically the size of each train car for each train.

For example, if the train was moving at 10 miles per second, and 10 train cars passed in one second, then each train car would be 1 mile long. If the other train was also moving at 10 miles per second and 20 train cars passed in one second, then one would know that each train car was 1/2 of a mile long for that train. This example shows that knowing the frequency of an electromagnetic wave gives you the wavelength, since all electromagnetic waves travel at the speed of light so that c = v (lambda) where v is frequency and lambda is wavelength, and c is the speed of light. Therefore, another way of expressing frequency is to say frequency is c over lambda.

References 

Physical quantity
Basic physics ideas
Wave physics
Mechanical vibrations
A hockey stick is a long, wooden pole used to push, pass, or shoot in the sports of ice hockey and field hockey. The art of developing ice hockey sticks is a complex science and has become big business. Ice hockey sticks are mostly made of composite materials and they have different "flexes", meaning some sticks are more flexible than others.
In ice hockey, the end or blade of the stick is normally curved, to help the player get better control of the puck and better shots at the goaltender.  The goaltender has a bigger blade, to make it easier to stop shots.  Players sometimes use hockey sticks to hold back the bodies of other players, or to trip or hit them; sometimes players who do this get penalties. In field hockey, sticks are shorter, but the blade is thicker, than in ice hockey.  It is used to move a ball instead of a puck. More research has gone into studying how hockey sticks perform. The main difference between the two sticks is how they are used in the games.

All the players in both ice and field hockey use hockey sticks.

References 

Sports equipment
Hockey
Calvin Cordozar Broadus Jr. (born October 20, 1971), known professionally as Snoop Dogg, is an American rapper, singer, songwriter, record producer and actor.

Early life
The reason why he is called "Snoop Dogg" is because his mother nicknamed him after a character called "Snoopy", because Snoop Dogg was a fan of the Peanuts cartoon, which has the Snoopy character.

Musical career

2012–2013: Reincarnated
In 2012, Snoop Dogg went to Jamaica. He studied the Rastafari movement. He changed his name to Snoop Lion, after the Lion of Judah. This is a name from the tribe of Judah. It is sometimes used to describe Haile Selassie, who is worshipped by Rastafarians. His 2013 album, Reincarnated, is his first reggae music album.

Discography

Studio albums
 Doggystyle (1993)
 Tha Doggfather (1996)
 Da Game Is to Be Sold, Not to Be Told (1998)
 No Limit Top Dogg (1999)
 Tha Last Meal (2000)
 Paid tha Cost to Be da Boss (2002)
 R&G (Rhythm & Gangsta): The Masterpiece (2004)
 Tha Blue Carpet Treatment (2006)
 Ego Trippin' (2008)
 Malice n Wonderland (2009)
 Doggumentary (2011)
 Reincarnated (2013)
 Bush (2015)
 Coolaid (2016)
 Neva Left (2017)
 Bible of Love (2018)
 I Wanna Thank Me (2019)
 From tha Streets 2 tha Suites (2021)
 The Algorithm (2021)

Collaboration albums
 Snoop Dogg presents Tha Eastsidaz with Tha Eastsidaz (2000)
 Duces 'n Trayz: The Old Fashioned Way with Tha Eastsidaz (2001)
 The Hard Way with 213 (2004)
 Mac & Devin Go to High School with Wiz Khalifa (2011)
 7 Days of Funk with 7 Days of Funk (2013)
 Royal Fam with Tha Broadus Boyz (2013)
 Cuzznz with Daz Dillinger (2016)

Filmography

References

Notes

Citations

Other websites

 
 Snoopdog TV on YouTube
 
 
 

1971 births
Living people
Actors from Long Beach, California
African-American movie actors
African American movie producers
African American musicians
African-American television actors
Rap musicians from California
American television producers
People from Long Beach, California
Singers from Los Angeles County, California
Gangsta rappers
Twitch (service) streamers
The Malayan tiger (Panthera tigris jacksoni) is a subspecies of the tiger that was discovered in 2004. People used to think they were Indo-Chinese tigers, But now they have their own subspecies. They have the same length and weight as the Indo-Chinese tiger. They live in southern Malaysia and they are an endangered species.

Related pages 
 Bali tiger
 Bengal tiger
 Caspian tiger
 Indochinese tiger
 Javan tiger
 Ngandong tiger
 Siberian tiger
 Sumatran tiger
 South China tiger
 Trinil tiger
 Wanhsien tiger

 

Tigers
Endangered species
The Caspian tiger (Panthera tigris virgata) is an extinct sub species of the tiger. It was the most western sub species of the tiger, very close to Europe. They became extinct in the 1970s. They were found in Turkey, Armenia, Iraq, Azerbaijan, Iran, Mongolia, and  Georgia.

Recent research by scientists looking at the tiger's DNA, have found that it is almost identical to the Siberian tiger. They now believe that the two species of tiger may not have become separate until the 1900s.

Description
The Caspian tiger was the second largest of the tiger species. It had a bigger, muscular body, with longer strong legs. It had large paws and more claws. It had small, short ears. The color was different from other tiger subspecies, with yellow to gold fur with light to dark brown stripes. The chest and stomach area are white with yellow stripes. In winter it grew longer fur. It was the furriest of all the tiger subspecies.

References

Tigers
Mammals of Pakistan
Extinct species
A string instrument is a musical instrument that makes sound by vibrating the strings on it. The strings are plucked to produce sounds. Each string has a different frequency. The desired frequency can be obtained by adjusting the tension on the string. A string instrument plays soft notes. The strings on the instrument usually come in many shapes and forms. There are many types of stringed instruments. The most common of these appear in the violin family. The violin is a small, stringed instrument played with a bow, usually made of horse's hair. When the bow is drawn across the strings it creates a vibration. You can select what vibration the bow makes by choosing the note on the fingerboard. It is tuned to G, D, A and E. The viola is a very similar instrument aside from some small differences - it is slightly larger, and is tuned to C, G, D, and A. The cello is a stringed instrument that is played in the bass clef. It is much bigger than the violin, and is also played much differently. The double-bass is bigger still and is the lowest of them all. 

There are also plucked strings, the most famous of which would probably be the guitar. The guitar uses a fret board and a pick to pluck the strings while holding down on the fret board. It was made famous by rock groups like Led Zeppelin and artists like Eric Clapton. You play by strumming with one hand while choosing notes on the fret-board (string board) with the other. Banjos are also very similar.

Here is a very basic list of some of the most common stringed instruments:

Guitar
Ukulele
Violin
Viola
Cello
String bass
Harp

Related pages
Musical instrument
Yankee Doodle Dandy is a 1942 biographical musical movie. It starred James Cagney as George M. Cohan.

Other websites 

1942 movies
American musical movies
American biographical movies
United States National Film Registry movies
English-language movies
Movies directed by Michael Curtiz
Guess Who's Coming to Dinner is a 1967 American comedy-drama movie, starring Spencer Tracy (in his final film role), Katharine Hepburn, Sidney Poitier and Katharine Houghton. It centers around what happens between a young white woman and her parents, after she falls in love with a black man in San Francisco.

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1967 comedy movies
1967 drama movies
1960s comedy-drama movies
American comedy-drama movies
Columbia Pictures movies
English-language movies
Movies about interracial romance
Movies set in San Francisco
American romantic comedy movies
American romantic drama movies
Movies directed by Stanley Kramer
Bringing Up Baby is a 1938 American comedy movie starring Cary Grant and Katharine Hepburn and directed by Howard Hawks. It is set in Connecticut.

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1938 movies
1930s comedy movies
1930s romance movies
American comedy movies
English-language movies
Movies set in Connecticut
United States National Film Registry movies
Movies directed by Howard Hawks
The Searchers is a 1956 epic western movie set in Texas in the 1860s. it is directed by John Ford and starring John Wayne, about a man looking for his niece who was taken by Native Americans. It is also one of the movies that influenced Star Wars.

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1956 movies
American western movies
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Movies set in Texas
Movies set in the 19th century
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1950s western movies
Movies directed by John Ford
Goodfellas is a 1990 American biographical crime movie directed by Martin Scorsese. It is about life in the Mafia.

It gained six nominations for Oscars. It won one (for Joe Pesci's role).  Many people thought the movie was great.

It is set in New York City. The movie is based on the life of mafioso Henry Hill (1943-2012) from 1955 - 1980. Goodfellas uses information from New York crime reporter Nicholas Pileggi's book Wiseguy.  Scorsese and Pileggi worked together to write the movie.

Goodfellas was first shown at the 1990 Venice Film Festival.  Scorsese received the Silver Lion award for Best Director.

Director David Chase said the movie made him want to make the HBO television series The Sopranos.

Cast

Awards

References

Other websites 

1990 crime movies
1990 drama movies
1990s biographical movies
1990s crime drama movies
Academy Award winning movies
American biographical movies
American crime drama movies
American gangster movies
BAFTA Award winning movies
English-language movies
Mafia
Movies directed by Martin Scorsese
Movies set in New York City
Movies set in the 1950s
Movies set in the 1960s
Movies set in the 1970s
Movies set in the 1980s
United States National Film Registry movies
A soldier is a person who is a part of an army. Soldiers have existed for many years, dating back to ancient times.

If people fight in irregular (not normal forces) armies not wearing a uniform, and not part of the official military (fighting group of a nation), they are called partisans if they fight against another nation's army, or terrorists, if they fight civilians. Partisans and terrorists are less protected by the laws of war than soldiers.

Soldiers can be volunteers or conscripts. A conscript is a person who has been forced to become a soldier and fight. In countries such as Switzerland, Israel, and Finland, men are conscripted for a few months once they become legal adults.

There are many different kinds of soldiers, and the term to describe them changes depending on their job and part of the military they serve in. For example, soldiers that serve in the navy can be called sailors or seamen.

Military ranks
The Yellowstone River is a river in the northwestern part of the United States.  It is a tributary of the Missouri River and flows through the states of Wyoming, Montana, and North Dakota. It also flows through Yellowstone National Park and feeds Yellowstone Lake. 

The Yellowstone River was first explored in 1806 by William Clark during the return trip of the Lewis and Clark Expedition.

Rivers of Montana
Rivers of North Dakota
Rivers of Wyoming
A toy is something to play with. Toys are for children, adults, and animals. Before 1970, most toys were made of metal and wood. Now, they are mostly made of plastic. Sometimes they are made of electronic material. Some people also consider video games toys. Toys include balls, plastic cars, and dolls. They also can be sex related products.

Toys originated many years ago. Dolls of infants, animals, and soldiers and toy tools are found in archaeological places. The origin of the word "toy" is not known. However, it is thought that it was first used in the 14th century.

The earliest toys were made from rocks, sticks or clay. In Ancient Egypt, children played with dolls made of clay and sticks. In Ancient Greece and Ancient Rome, children played with dolls made of wax or terracotta, sticks, bows and arrows, and yo-yos. Later these developmental games were used in creation of indoor playsets for homes. When Greek children, especially girls became adults, it was required to sacrifice the toys to the gods. On the eve of their wedding, young girls around fourteen would offer their dolls in a temple as a rite of passage into adulthood.

Gallery

References
A unicorn is a legendary and mythical creature. It looks like a pony with one long, single and white  horn on its head. The word unicorn means literally "one-horn". It comes from the Latin word ūnus, which means one, and cornu which means horn, which term is in itself borrowed from the earlier Greek word monokerōs (also 'one horned').

Unicorns are found in many stories and myths from different parts of the world, especially China and India. Its blood and horn usually have mystical powers. In Western culture, its horn is said to have power (often called alicorn in medieval literature) to heal wounds and sickness, and to neutralize poison.

In mythology and heraldry unicorn symbolizes innocence, purity and feminine power. It is often seen as the counterpart of lion, which symbolizes the masculine virtues.

The unicorn is the official animal of Scotland.

In some pictures unicorns also have horses feet or a lion's tail. 

A Narwhal is an animal that is about 8 feet long. They live in the water around Canada and Greenland. Narwhal’s horns were said to be the horns of unicorns by some. People would sell the horn of a narwhal to others and say it was a horn of a unicorn.
Christian legends say the Unicorn is as small as a normal sized goat. They are so fearful that no hunter can catch them. Only a maiden that goes into the forest alone can catch a unicorn. The unicorn will come and fall asleep in the maiden’s lap. Around the time of the Middle Ages, some stories of unicorns became more popular. People bought what were said to be the horns of a unicorn at very high prices. They were mostly a tusk of a walrus or a horn from a narwhal. 

The term unicorn is also used in business to refer to a business startup valued at a billion dollars or more.

Real animals

Unicorns in history 
In On the Nature of Animals (Περὶ Ζῴων Ἰδιότητος, De natura animalium), Aelian, quoting Ctesias, adds that India has also a one-horned horse (iii. 41; iv. 52), and says (xvi. 20) that the monoceros () was sometimes called cartazonos (), which may be a kind of the Arabic karkadann, meaning "rhinoceros".

References

Sources
 Lindahl, Carl. "Unicorn." World Book Advanced. World Book, 2012. Web.  29 Nov. 2012.
 SuperScience: Mythical Creatures Revealed. Scholastic, May 2006. Web. 29 Nov. 2012. <http://www.scholastic.com/browse/article.jsp?id=11851 >.

Legendary creatures
Darwin is the territorial capital of the Northern Territory in Australia. The city has about 147,000 people living there. The city is named after Charles Darwin. A member of the crew of the ship that started a port there in 1839 named it Port Darwin in honor of Darwin, who had sailed on that same ship earlier.
Most of Darwin has been built since 1974, when Cyclone Tracy ripped through and destroyed the city. Since then, the city has recovered. It is a very important port, because it is on the coast closest to Indonesia and the rest of Asia. Darwin also has a large military base.

Darwin also has many Indigenous Australians living in the city, about 9.7% of the people. This is more than any other state capital in Australia.

References

Other websites
 

Capital cities in Australia
Cities in the Northern Territory
The Northern Territory is a territory of Australia. The capital city is Darwin. Other large towns in the Territory include Alice Springs, Katherine and Tenant Creek.

The Northern Territory has large areas of desert. It has many important places such as Uluru, or Ayers Rock. The rock is sacred to the native people.

Kakadu National Park is a World Heritage area. It has been lived in for more than 40,000 years. There are cave paintings, rock carvings and archaeological sites. These show the skills and way of life of the people who have lived there. The park has different ecosystems, including tidal flats, floodplains, lowlands and rocky gorges. It provides a place to live for a wide range of rare types of plants and animals.

Floral Emblem 

The floral emblem of the Northern Territory is Sturt's Desert Rose, Gossypium sturtianum. The flower is also featured on the Territory's flag. It was named after explorer Charles Sturt who found the plant in creeks near the site of Broken Hill, New South Wales in 1844.
The Fauna emblem is the Red Kangaroo.

References
The Whiskey Rebellion was a rebellion against the federal government of the United States. Some farmers in western Pennsylvania rebelled against the United States government in 1794 because they believed that a new tax on whiskey was not fair. Selling whiskey was how people traded in western Pennsylvania, but farmers elsewhere did not need to sell whiskey. 

The United States had borrowed a large amount of money for the American Revolutionary War, and Alexander Hamilton offered the idea to try to pay the war debt. The government under George Washington, with advice from Alexander Hamilton, quickly stopped the rebellion. Washington and Hamilton wanted to ensure that no one would question the power of the federal government and so Washington himself led almost 13,000 troops to stop the rebellion of a few hundred farmers. The rebels went home before the army arrived.

The new federal government became more solid and the president more powerful. Numerous examples of resistance are recorded in court documents and newspaper accounts.

That is the only time in American history that a president has led the army by himself.

References 

1794
18th century rebellions
Whisky
1790s in Pennsylvania
Thomas Cruise Mapother IV (; born July 3, 1962), widely known as Tom Cruise, is an American movie actor and producer. He has starred in many movies, including War of the Worlds and Jerry Maguire. He is one of the highest paid actors in Hollywood.

His first movie was Endless Love.  His first leading role was in the movie Risky Business.  He has been nominated for three Academy Awards and has won three Golden Globe Awards.  These were for the same movies: Born on the Fourth of July (1989), Jerry Maguire (1996), Magnolia (1999).

Early life
Tom Cruise was born in Syracuse, New York. He is the son of Mary Lee, a special education teacher, and Thomas Cruise Mapother III (died 1984), an electrical engineer. Cruise has three sisters, Lee Anne, Marian, and Cass. Cruise's surname originates from his great-grandfather, born Thomas Cruise O'Mara, who was renamed "Thomas Cruise Mapother" (Mapother is a Welsh surname). Cruise is of Irish, German and English ancestry. One of his paternal great-great-great-grandfathers, Patrick Russell Cruise, was born in North County Dublin, in 1799; he married Teresa Johnson in Warrenstown House, County Meath, in 1825. They left Ireland for America that same year and settled in New York.

Personal life
Cruise is a Scientologist. He is one of the most famous members of the organization.

Cruise has an adopted daughter and adopted son with his second wife Nicole Kidman. He has a daughter Suri (born April 2006), by Katie Holmes. He and Holmes married in November 2006 and separated in 2012.

References

Other websites

 

Actors from New York
American movie actors
American movie producers
People from Syracuse, New York
Scientologists
1962 births
Living people
There is also the alternative metal band Orgy (band).

In common use, an orgy is when more than two people have sex together, sometimes also called group sex.
This dates back to prehistoric ages, recorded in many ancient civilizations. 

Orgy could also mean any activity done without limits.

Originally, the word comes from Latin. There it referred to a feast (or a banquet) of a rich citizen. When the Romans ate they were almost lying down, and the food was brought to them by slaves. These slaves would also provide the entertainment which usually consisted of music and dancing slaves.

Sexuality
Human sexuality