Name: ______________________

Quiz 1

02/07/2006

Ch. 16

The speed of sound in air is 344 m/s.

1)      You and your friend have forgotten the speed of sound in steel.  Luckily you are standing next to a long steel fence.  Each of you jogs along the fence in opposite directions for about 20 min.   Then you call your friend on their cell phone.  You put your ear on the fence and direct your friend hit the fence hard with a pipe on your command.  Using your trusty stopwatch you measure the time it take for the sound to reach you through the steel fence to be 0.82 seconds and the time for the sound to reach you through the air to be 14.35 seconds.  What is the speed of sound in the steel fence?   You may ignore the time it takes for you to signal your friend using your cell phone.

2)      You are sitting on the side of and empty swimming pool kicking your feet back and forth 3 times per second creating a wave.  You adjust the strength of your kicks so that the peaks of the wave just reach the top edge of the pool 15 cm above the level of the water when it is still.  You measure 30 seconds between the time you create a wave and it reaches the other side of the pool 10 meters away.

a)      What is the amplitude of the waves?

b)      What is the period of the waves?

c)      What is the frequency of the waves?

d)      What is the speed of the waves?

e)      What is the wavelength of the waves?

f)        Write an equation for the wave height y(x,t), where x is the distance from the side of the pool where your feet are, and t is the time.  (Assume the wave shape is a sine function.)