Chapter 14: Waves and Sound
Physlet® Problems



1.  

Find the frequency of the wave shown in the above animation (position is in centimeters and time is in seconds). Start

4.0 cycles/second.
2.0 cycles/second.
0.5 cycles/second.

2.  

Find the velocity of the wave shown in the above animation (position is in centimeters and time is in seconds). Start

-8.0 cm/second.
8.0 cm/second.
-4.0 cycles/second.

3.  

The above simulation shows disturbances on two identical strings (position is in centimeters and time is in seconds).  What is the tension in the second string if the tension in the first string is 500 N? Start

The tension is the same in both strings
The tension is the same in both strings
The tension in the bottom string is half that of the top string.
The tension in the bottom string is four times that of the top string.

4.  

The above simulation shows disturbances on two identical strings (position is in centimeters and time is in seconds). At t=2.5 seconds which of the following is true regarding the superposition of the two waves? Start
Their sum adds up to zero.
Their sum adds up to twice the original waves.
Their sum is as if only one of the original waves is there.
Their sum has a large peak a depression and then another large peak.

5.  

The above simulation shows disturbances on two identical strings (position is in centimeters and time is in seconds). At t=2.5 seconds which of the following is true regarding the superposition of the two waves? Start
Their sum adds up to zero.
Their sum adds up to twice the original waves.
Their sum is as if only one of the original waves is there.
Their sum has a large peak a depression and then another large peak.

6.  

Why are there no dead spots in the sound distribution when either the left or the right source is transmitting but there are multiple dead spots when both sources are transmitting (position is in centimeters and time is in seconds)?
Either source can block the sound wave from leaving the other from transmitting a wave.
Wave superposition produces interference effects.
Refraction bends the waves.

7.  

The above simulation shows how two waves can add together to produce a standing wave on a string (position is in centimeters and time is in seconds). The third panel represents the string. The waves in the first two panels have been superimposed to produce the wave in the third panel.  Which of the following statements is true? Start

Waves never pass through the point x=0 on the string since this point never moves.
The string is perfectly straight when the maxima in the first two panels overlap.
There is an instant in time when the string does not move.
The string is moving fastest when the maxima in the first two panels overlap.

8.  

The above simulation shows a standing wave on a string (position is in centimeters and time is in seconds).  With what speed do waves propagate on this string? Start

0.0 m/s
4.0 m/s
15 m/s
The answer depends on where along the wave the measurement is made.

9.  

The above simulation shows a standing wave on a string (position is in meters and time is in seconds).  If the tension in the string is 4 N, determine the mass of the string. Start

4000 kg
70.5 grams
.70 grams
90 grams

10.  

The above simulation shows a superposition of two waves on identical strings (position in meters and time is in seconds).  What is the difference in frequency between the two waves? Start

0 Hz
4 Hz
0.25 Hz
The answer depends on where along the wave the measurement is made.

11.  

The animation represents a cross section of a three dimensional sound wave propagating away from a moving source.  In which of the animation(s) is the source traveling slower than the speed of sound?
Animations 1, 2, 3
Animations 1 and 2
Animations 4 and 5
Insufficient information. 

12.  

You are standing besides a highway as a police car, with its sirens on, drives by as shown in the animation (position is in meters and time is in seconds). Which of the following animations represents what you would hear?

Animation 1
Animation 2
Animation 3
Animation 4

13.  

The animation represents a cross section of a three dimensional sound wave propagating away from a moving source.  In which of the animations does the resulting sound wave travel the fastest?
Animation 1
Animation 5
All tie
Depends on the observer's location

14.  

You are standing besides a highway as a police car, with its sirens on, drives by as shown in the animation (position is in meters and time is in seconds). Given the frequency of the siren as 800 Hz, determine the change in frequency you will hear as the police car goes by. Start

-24 Hz
-46.7 Hz
46.7 Hz

Physlets used by permission of Wolfgang Christian, Davidson College. Physlet Problems ©Prentice Hall, Inc. Physlet problems on this web site were written by Wolfgang Christian, Mario Belloni, and Aaron Titus.


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