How does the piano produce vibrations?

for every key, there is a string in the back. When you hit the key, the key makes a hitter bounce of the string

For a start,,, a PIANO does not vibrate and create a sound, its components resonate in sympathy for the frequency being created by the action, which is the key being struck, then the hammer striking the string/s(very simply put!).

For every key on a piano, there is a hammer inside. When a key is struck, the hammer hits either one, two or three strings, depending on the note. Usually, the 10 lowest pitches have a single string with copper, copper-clad or brass wire wound round it, then the next 18 pitches have two strings and then the last 60 have three strings per hammer (note). These sets of strings are called unisons, as they vibrate at the same frequency (rate of traveling back and forth).

Every note sounded on a piano is the result of a string, or set of two or three strings, vibrating at a specific frequency determined by the length, diameter, tension and density(/structure) of the wire. A shorter, lighter string, under more tension, vibrates faster, and produces a higher-pitched sound.

Strings vibrate, causing the air particles to vibrate, causing your eardrum to vibrate.

If it was just the strings vibrating that made the sound of the piano, then it would just sound like plucking a piece of wire, quite a pure, quiet sound. But it doesnt, because you have overtones all coming togather to create the final sound. To amplify the sound of the strings, they press down on a bridge which conducts their vibration to the large, thin piece of wood called the soundboard.

This is a very breif description of how a piano works. Forgive me if I have missed anything, but I haven't much time. I am doing an assignment on the fundamental principals involved in the sound production of an acoustic instrument, and guess what acoustic instrument I'm doing........