the physics of a guitar
1.standing waves
nodes: don't move at all
anti-nodes: vibrate back and forth
2. pluck the guitar strings→create vibration called standing waves→vibration translate through the guitar's neck and bridge to the body, where thin and flexible wood vibrates→stir the air molecules together and apart→sequential compressions create sound waves，most escape from the holes of guitar→eventually propagate to your ear which translate them into electrical impulses→your brain interpret them into sounds
3.vibration frequency
（1）quicker vibration→closer compression→high pitch sounds
（2）four factors determining the frequency: length,tension(similar) density,thickness(thicker, less vibration lower notes)
4. fundamental wave and overtones combine to produce complex wave with rich sound.
change overtones by changing the way you pluck the guitar: pluck in the middle produce fundamental and odd multiple waves； pluck in the bridge produce even multiple waves and twang.
5. electrical guitar
vibrate in the strings→translate into electrical signals by pickups→（sound process）translate to speakers creating sound waves
