TUTORIAL Questions 30-40

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30: Transmission of sound waves.
33: Atmospheric pressure
35: Echo
40: "The Shive"


Question 30. Sometimes you can hear faintly somebody speaking behind a wall in the room next to you because:

a)  air molecules penetrate the wall and transmit the sound wave.
b)  sound waves can sneak through tiny openings in the wall
c)  part of the original sound wave is transmitted through the wall
d)  the original sound wave breaks apart when it hits the wall and regenerates
  itself on the other side of the wall.
e)  none of the above

Fundamentals of Sound reference: Sec. 1-J.


Question 33. Why don't the forces exerted inward on our bodies by the atmoshphere crush our bodies?

a)  The forces are too small due to low air density.
b)  The outer surfaces of body cells are sufficiently strong.
c)  The pressure inside our bodies is the same as outside.
d)  It is a mystery of nature.

Fundamentals of Sound reference: Sec. 1-I.


Question 35. The echo heard after clapping your hands in a canyon is an example of which of these?

a)  The original sound wave dying out when it hits the canyon wall
b)  The original sound wave reflecting from the canyon wall
c)  The canyon wall generating its own sound wave in response to the original sound wave
d)  The original sound wave breaking the sound barrier while you are in the canyon
e)  None of the above

Fundamentals of Sound reference: Sec. 1-J.


Question 40. The "Shive" wave machine is a series of horizontal bars each welded to an elastic wire running perpendicularly to the centers of the bars, so that lifting one bar causes the next to rise (because of the twist of the connecting wire) and a transverse wave will propagate. For a picture click here.
What is the propagation speed (or wave velocity) of the wave?

You may use some or all of the following information;
*    The distance from the first rod to the last rod is 3 feet.
*    Each rod goes up a total of 1/2 foot as the wave goes by.
*    It takes each rod 1 second to travel the 1/2 foot as the wave goes by.
*    It takes 2 seconds for the wave to travel to the end of the Shive from the first rod where it was generated.

a)  1/4 ft/s
b)  1/2 ft/s
c)  1ft/s
d)  3/2 ft/s
e)  2ft/s

Fundamentals of Sound reference: Sec. 1-C.

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© William J. Mullin