Max+Weisman

__//**The Terrific Tuning Fork**//__


A tuning fork is a set of metal prongs that vibrate back and forth and resonate at a certain pitch, which changes depending on the length of the prongs. A longer fork will make a deeper note, and a shorter fork will make a higher noise. When the two prongs vibrate, they compress the air molecules around them, and then cause rarefraction, which is the opposite of compression. This happens because the fork vibrates back and fourth, it causes compression and between vibrations there's a "dead" point where the rarefraction happens. To make the tuning fork work, all you have to do is hit it on a surface, and listen for the sound! Many musicians use a tuning fork due to the fact that the fork never goes out of tune (unless it's damaged). It will never go out of tune because it's made at a certain pitch, there's no strings to loosen, to screws to tighten, only a metal fork. Some doctors use a tuning fork to test for hearing loss. What they'll do is hit the fork on a surface and see how long the person can hear the noise, compared to how long they can feel the vibrations in their jaw. If someone is unable to get an x-ray but thinks that their bone is fractured, they can use a tuning for and put it next to the bone they think is hurt, if it hurts it's probably fractured.

Compression and rarefraction:



Equation to find the frequency of the particular tuning fork:



f is the frequency

1.875 the smallest positive solution of cos(x)cosh(x) = -1

l is the length of the prongs in meters

E is the elastic modulus of the material the fork is made of (the stiffness of the material)

I is the second moment of area

p is the density of the material the tuning fork is made out of

A is the area between the prongs of the fork

Sound, Waves, Pressure

Reference:

http://learn.uci.edu/media/OC08/11004/OC0811004_TuningFork.jpg

http://upload.wikimedia.org/math/a/4/b/a4b8dbb2f48194067178d23b486bfa43.png

http://en.wikipedia.org/wiki/Tuning_fork

http://science.howstuffworks.com/tuning-fork1.htm

http://www.physicsclassroom.com/class/sound/u11l1c.cfm