A cantata is a type of singing which is done accompanied by an instrument(s). By contrast, a cappella specifically refers to unaccompanied singing. The word(cantata) etymologically comes from the Italian word “cantare” which meant “to sing”. The word “cantata” was used mainly in the 17th and 18th century to describe music with religious words that were sung by a choir or by soloists or both, accompanied by instruments. The most famous cantatas are those by Johann Sebastian Bach. Nearly all his cantatas are sacred(written for church services). Very often he used Lutheran hymn tunes (chorales) for the first and last movements. In between there are movements for solo singers: recitatives and arias. A famous example is Bach's cantata no 80 which is based on the chorale “Ein feste Burg ist unser Gott(“A safe stronghold our God is still”). The whole work is about being safe in the hands of God. This is what the sermon would have been about. The congregation would join in singing the chorale towards the end of the cantata.
Other composers, such as Alessandro Scarlatti (1660-1725) wrote cantatas which were secular(not religious). The word “cantata” has also been used in the 20th century by composers such as Igor Stravinsky (1882-1971) and Benjamin Britten (1913-1976).
Thus the term came to apply to any and all forms of accompanied songs.
Clavichord
A clavichord is a musical instrument like a small keyboard. It was very popular for many years, especially in the 16th, 17th and 18th centuries.
The clavichord is a very quiet instrument. It was not suitable for playing with other instruments because it was so quiet. But it sounds very beautiful in slow, expressive music. It was used as a practice instrument by harpsichord players, or by organists who wanted to practise at home instead of in a (often very cold) church. They were so small that they could be lifted up and put on a table. They could be put one on top of another so that an organist could practise music written for a two-manual organ. Sometimes they even had pedals for organists to practise this skill.
Many German composers like Johann Sebastian Bach wrote music for the “Clavier”. This meant any keyboard instrument: harpsichord, clavichord or organ. The player could choose which they wanted to use.
When the piano suddenly became popular – in the 1760s and 1770s – people started to forget about harpsichords and clavichords. Today a few people make harpsichords and clavichords again so that people can play Renaissance and Baroque music - the music from when the clavichord was popular.
Harmony
Harmony means playing several notes together to make “chords”. The word comes from the Greek "harmonia" meaning "to join things up" . A tune by itself can sound nice, but it can be “harmonized” by adding an accompaniment of chords. Studying how to do this is called harmonization. Music students learn which chords sound nice after one another. These are called “chord progressions”. Many music theorists have written books about harmony.
Music which is made of a tune with harmony underneath is called “homophonic”. In a way it is the opposite of polyphonic which means that each part (each voice) is a tune in itself. However, even polyphony needs to make pleasant harmony. Harmony as we know it in European music had become fully developed by the Baroque period (17th century).
One can play a chord with three notes using the 1st, 3rd and 5th notes of the scale of whatever key the music is in. This gives a chord which sounds like the “home chord”. This means that at least three notes are needed for harmony. In most homophonic music there are four: for example a choir will normally divide into soprano, alto, tenor and bass, or a string quartet will divide into violin 1, violin 2, viola and cello.
Harmony which uses just the notes of the key (e.g. just using white notes for C major) is called “tonal harmony”.
Harmony which adds lots of extra sharps and flats is called “chromatic harmony”.
If music is not in any key at all, like in some music by Arnold Schoenberg, it is “atonal”. Harmony can be atonal.
Bow (weapon)
A bow is a weapon used to shoot arrows. It is used in hunting, sport, and a long time ago, war.
Using a bow is called archery. A person who uses a bow is an archer and a person who makes bows is a bowyer.
A bow is a long curved stick and a string which is tied to both ends. Ancient bows were made of natural materials like wood or bone and sinew, but today they are often made of plastic and similar materials.
To shoot a bow, the arrow is put on the bow, with one end to the string, which is pulled back. When the string is let loose, it throws the arrow forwards.
There are many different types of bows, for example the longbow or the automatic crossbow
and the compound bow.
There are many different ways that people protect themselves from arrow attacks. The Roman Army, for instance, had the testudo formate, or tortoise formation. They first made the shields lock into a somewhat tortoise like formation, which provide a shell that was make out of shields. The arrows would eventually run out, and the Romans would charge.
Nuclear physics
Nuclear physics is the part of physics that studies the nucleus of the atom. Everything on the earth is made up of atoms; they are the smallest part of a chemical element that still has the properties of that specific element. When two or more atoms combine they create what we know as the molecule, which is the smallest part of a chemical compound which still has the properties of that specific compound. Understanding the structure of atoms is key in studies such as physics, chemistry, biology, etc.
Atoms are made up of electrons, neutrons, and protons. The protons and neutrons are in the center of the atom, which is called the nucleus. The protons and neutrons are the heaviest part of the atom and make up most of its mass. The electrons move around the nucleus very quickly, making what is called an electron cloud. The electron cloud has a very small mass, but it makes up most of the space of the atom. The electrons have a negative charge, and the protons have a positive charge. Due to the charges in the atom, that is how the atom stays together, by attraction of the electric charges present in the atom.
Atoms have different features that single out one atom from another, and show how each atom can change in different conditions. These properties include atomic number, mass number, atomic mass and weight, and isotopes.
In an atom there are three fundamental forces that keep atoms together. electromagnetic force, strong nuclear force, and weak nuclear force. The electromagnetic force keeps the electrons attached to the atom. The strong nuclear force keeps the protons and neutrons together in the nucleus. The weak nuclear force controls how the atom decays.
In the early 20th century, scientists had trouble explaining the behavior of atoms using their current knowledge of matter. So to deal with this they made a brand new way to view matter and energy, and they called it quantum theory. Quantum theory explains how matter acts both as a particle and a wave.
Atoms emit radiation when their electrons lose energy and drop down to lower orbitals. The difference in energy between the orbitals determines the wavelength of the given radiation. This radiation can be shown by visible light or shorter wavelengths.
Seljuk Empire
Not to be Confused with Seljuk Sultanate of Rûm
The Seljuk Empire was an empire of the Seljuk Turks and a Muslim dynasty. It ruled parts of Central Asia and the Middle East from the 11th to the 14th centuries. It was founded by Tughril Beg in 1037. The Seljuk Empire stretched from Anatolia to Pakistan. It was replaced by the Khwarezmian Empire in 1194.