Question 1

If y = 0.02 sin (30x − 400t) (SI units), the velocity of the wave is

Accepted Answer

A)  3/40 m/s 
B)  40/3 m/s 
C)  60π/400 m/s 
D)  400/60π m/s 
E)  400 m/s 
A)  3/40 m/s 
B)  40/3 m/s 
C)  60π/400 m/s 
D)  400/60π m/s 
E)  400 m/s

Question 2

What is the expression for the transverse velocity of the wave in a string given by   ?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 3

A sculptor strikes a piece of marble with a hammer. Find the speed of sound through the marble (in km/s). (The Young's modulus is 50 × 109 N/m2 and its density is 2.7 × 103 kg/m3.)

Accepted Answer

A)  5.1 
B)  4.3 
C)  3.5 
D)  1.3 
E)  1.8 
A)  5.1 
B)  4.3 
C)  3.5 
D)  1.3 
E)  1.8

Question 4

An earthquake emits both S-waves and P-waves which travel at different speeds through the Earth. A P-wave travels at 9 000 m/s and an S-wave travels at 5 000 m/s. If P-waves are received at a seismic station 1.00 minute before an S-wave arrives, how far away is the earthquake center?

Accepted Answer

A)  88.9 km 
B)  1 200 km 
C)  675 km 
D)  240 km 
E)  480 km 
A)  88.9 km 
B)  1 200 km 
C)  675 km 
D)  240 km 
E)  480 km

Question 5

A stone is thrown into a quiet pool of water. With no fluid friction, the amplitude of the waves falls off with distance r from the impact point as

Accepted Answer

A)  1/r3 
B)  1/r2 
C)  1/r3/2 
D)  1/r1/2 
E)  1/r 
A)  1/r3 
B)  1/r2 
C)  1/r3/2 
D)  1/r1/2 
E)  1/r

Question 6

The wavelength of light visible to the human eye is on the order of 5 × 10−7 m. If the speed of light in air is 3 × 108 m/s, find the frequency of the lightwave.

Accepted Answer

A)  3 × 107 Hz 
B)  4 × 109 Hz 
C)  5 × 1011 Hz 
D)  6 × 1014 Hz 
E)  4 × 1015 Hz 
A)  3 × 107 Hz 
B)  4 × 109 Hz 
C)  5 × 1011 Hz 
D)  6 × 1014 Hz 
E)  4 × 1015 Hz

Question 7

The velocity of sound in sea water is 1.53 × 103 m/s. Find the bulk modulus (in N/m2) of sea water if its density is 1.03 × 103 kg/m3.

Accepted Answer

A)  2.57 × 109 
B)  2.19 × 109 
C)  2.04 × 109 
D)  2.41 × 109 
E)  2.82 × 109 
A)  2.57 × 109 
B)  2.19 × 109 
C)  2.04 × 109 
D)  2.41 × 109 
E)  2.82 × 109

Question 8

Exhibit 16-1
The figure below shows a sine wave at one point of a string as a function of time.   Use the exhibit to answer the following question(s).
-Refer to Exhibit 16-1. Which of the graphs below shows a wave where the amplitude and frequency are each reduced in half?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 9

A piano wire of length 1.5 m vibrates so that one-half wavelength is contained on the string. If the frequency of vibration is 65 Hz, the amplitude of vibration is 3.0 mm, and the density is 15 g/m, how much energy is transmitted per second down the wire?

Accepted Answer

A)  21 W 
B)  11 W 
C)  5.4 W 
D)  2.2 W 
E)  1.1 W 
A)  21 W 
B)  11 W 
C)  5.4 W 
D)  2.2 W 
E)  1.1 W

Question 10

A spherical wave has the form   . The wavelength of the wave is

Accepted Answer

A)  0.25 m. 
B)  0.50 m. 
C)  4.0 m. 
D)  8.0 m. 
E)  4.0π m. 
A)  0.25 m. 
B)  0.50 m. 
C)  4.0 m. 
D)  8.0 m. 
E)  4.0π m.

Question 11

The speed of a 10-kHz sound wave in seawater is approximately 1 500 m/s. What is its wavelength in sea water?

Accepted Answer

A)  5.0 cm 
B)  10 cm 
C)  15 cm 
D)  20 cm 
E)  29 cm 
A)  5.0 cm 
B)  10 cm 
C)  15 cm 
D)  20 cm 
E)  29 cm

Question 12

A friend hands you an equation sheet with the following equation for the Doppler effect:   . This version of the equation is correct with signs as given only if

Accepted Answer

A)  the observer and source are approaching each other. 
B)  the observer is approaching the source while the source is moving away from the observer. 
C)  the observer is moving away from the source while the source is approaching the observer. 
D)  the observer and source are moving away from each other. 
E)  the observer and source are moving in perpendicular directions. 
A)  the observer and source are approaching each other. 
B)  the observer is approaching the source while the source is moving away from the observer. 
C)  the observer is moving away from the source while the source is approaching the observer. 
D)  the observer and source are moving away from each other. 
E)  the observer and source are moving in perpendicular directions.

Question 13

If y = 0.02 sin (30x − 400t) (SI units), the wave number is

Accepted Answer

A)  30 rad/m 
B)  30/2π rad/m 
C)  400/2π rad/m 
D)  400 rad/m 
E)  60π rad/m 
A)  30 rad/m 
B)  30/2π rad/m 
C)  400/2π rad/m 
D)  400 rad/m 
E)  60π rad/m

Question 14

A jet plane has a sound level of 150 dB. What is the intensity in W/m2?

Accepted Answer

A)  1 
B)  100 
C)  10 
D)  1 000 
E)  10 000 
A)  1 
B)  100 
C)  10 
D)  1 000 
E)  10 000

Question 15

When you hear the horn of a car that is approaching you, the frequency that you hear is larger than that heard by a person in the car because for the sound you hear

Accepted Answer

A)  wave crests are farther apart by the distance the car travels in one period. 
B)  wave crests are closer together by the distance the car travels in one period. 
C)  the car gets ahead of each wave crest before it emits the next one. 
D)  the speed of sound in air is increased by the speed of the car. 
E)  a speeding car emits more wavecrests in each period. 
A)  wave crests are farther apart by the distance the car travels in one period. 
B)  wave crests are closer together by the distance the car travels in one period. 
C)  the car gets ahead of each wave crest before it emits the next one. 
D)  the speed of sound in air is increased by the speed of the car. 
E)  a speeding car emits more wavecrests in each period.

Question 16

A student attaches a length of nylon fishing line to a fence post. She stretches it out and shakes the end of the rope in her hand back and forth to produce waves on the line. The most efficient way for her to increase the wavelength is to

Accepted Answer

A)  increase the tension on the hose and shake the end more times per second. 
B)  decrease the tension on the hose and shake the end more times per second. 
C)  increase the tension on the hose and shake the end fewer times per second. 
D)  decrease the tension on the hose and shake the end fewer times per second. 
E)  keep the tension and frequency the same but increase the length of the hose. 
A)  increase the tension on the hose and shake the end more times per second. 
B)  decrease the tension on the hose and shake the end more times per second. 
C)  increase the tension on the hose and shake the end fewer times per second. 
D)  decrease the tension on the hose and shake the end fewer times per second. 
E)  keep the tension and frequency the same but increase the length of the hose.

Question 17

You are holding on to one end of a long string that is fastened to a rigid steel light pole. After producing a wave pulse that was 5 mm high and 4 cm wide, you want to produce a pulse that is 6 cm wide and 7 mm high. You must move your hand up and down once,

Accepted Answer

A)  the same distance up as before, but take a shorter time. 
B)  the same distance up as before, but take a longer time. 
C)  a smaller distance up, but take a shorter time. 
D)  a greater distance up, but take a longer time. 
E)  a greater distance up, but take the same time. 
A)  the same distance up as before, but take a shorter time. 
B)  the same distance up as before, but take a longer time. 
C)  a smaller distance up, but take a shorter time. 
D)  a greater distance up, but take a longer time. 
E)  a greater distance up, but take the same time.

Question 18

A point source emits sound with a power output of 100 watts. What is the intensity (in W/m2) at a distance of 10.0 m from the source?

Accepted Answer

A)  7.96 × 10−2 
B)  7.96 × 10−1 
C)  7.96 × 100 
D)  7.96 × 101 
E)  7.96 × 10−3 
A)  7.96 × 10−2 
B)  7.96 × 10−1 
C)  7.96 × 100 
D)  7.96 × 101 
E)  7.96 × 10−3

Question 19

You are holding on to one end of a long string that is fastened to a rigid steel light pole. After producing a wave pulse that was 5 mm high and 4 cm wide, you want to produce a pulse that is 4 cm wide but 7 mm high. You must move your hand up and down once,

Accepted Answer

A)  the same distance up as before, but take a shorter time. 
B)  the same distance up as before, but take a longer time. 
C)  a smaller distance up, but take a shorter time. 
D)  a greater distance up, but take a longer time. 
E)  a greater distance up, but take the same time. 
A)  the same distance up as before, but take a shorter time. 
B)  the same distance up as before, but take a longer time. 
C)  a smaller distance up, but take a shorter time. 
D)  a greater distance up, but take a longer time. 
E)  a greater distance up, but take the same time.

Question 20

Exhibit 16-3
Four wave functions are given below.
I.y(x, t) = 5sin(4x - 20t + 4)
II.y(x, t) = 5sin(3x - 12t + 5)
III.y(x, t) = 5cos(4x + 24t + 6)
IV.y(x, t) = 14cos(2x - 8t + 3)
Use this exhibit to answer the following question(s).
-Refer to Exhibit 16-3. Rank the wave functions in order of the magnitude of the frequencies of the waves, from least to greatest.

Accepted Answer

A)  IV, II, I, III 
B)  IV = II, I, III 
C)  III, I, II, IV 
D)  IV, I, II, III 
E)  III, IV, II, I 
A)  IV, II, I, III 
B)  IV = II, I, III 
C)  III, I, II, IV 
D)  IV, I, II, III 
E)  III, IV, II, I

Exam 16: Wave Motion

If y = 0.02 sin (30x − 400t) (SI units), the velocity of the wave is

What is the expression for the transverse velocity of the wave in a string given by ?

A sculptor strikes a piece of marble with a hammer. Find the speed of sound through the marble (in km/s). (The Young's modulus is 50 × 109 N/m2 and its density is 2.7 × 103 kg/m3.)

An earthquake emits both S-waves and P-waves which travel at different speeds through the Earth. A P-wave travels at 9 000 m/s and an S-wave travels at 5 000 m/s. If P-waves are received at a seismic station 1.00 minute before an S-wave arrives, how far away is the earthquake center?

A stone is thrown into a quiet pool of water. With no fluid friction, the amplitude of the waves falls off with distance r from the impact point as

The wavelength of light visible to the human eye is on the order of 5 × 10−7 m. If the speed of light in air is 3 × 108 m/s, find the frequency of the lightwave.

The velocity of sound in sea water is 1.53 × 103 m/s. Find the bulk modulus (in N/m2) of sea water if its density is 1.03 × 103 kg/m3.

Exhibit 16-1 The figure below shows a sine wave at one point of a string as a function of time. Use the exhibit to answer the following question(s). -Refer to Exhibit 16-1. Which of the graphs below shows a wave where the amplitude and frequency are each reduced in half?

A piano wire of length 1.5 m vibrates so that one-half wavelength is contained on the string. If the frequency of vibration is 65 Hz, the amplitude of vibration is 3.0 mm, and the density is 15 g/m, how much energy is transmitted per second down the wire?

A spherical wave has the form . The wavelength of the wave is

The speed of a 10-kHz sound wave in seawater is approximately 1 500 m/s. What is its wavelength in sea water?

A friend hands you an equation sheet with the following equation for the Doppler effect: . This version of the equation is correct with signs as given only if

If y = 0.02 sin (30x − 400t) (SI units), the wave number is

A jet plane has a sound level of 150 dB. What is the intensity in W/m2?

When you hear the horn of a car that is approaching you, the frequency that you hear is larger than that heard by a person in the car because for the sound you hear

A student attaches a length of nylon fishing line to a fence post. She stretches it out and shakes the end of the rope in her hand back and forth to produce waves on the line. The most efficient way for her to increase the wavelength is to

You are holding on to one end of a long string that is fastened to a rigid steel light pole. After producing a wave pulse that was 5 mm high and 4 cm wide, you want to produce a pulse that is 6 cm wide and 7 mm high. You must move your hand up and down once,

A point source emits sound with a power output of 100 watts. What is the intensity (in W/m2) at a distance of 10.0 m from the source?

You are holding on to one end of a long string that is fastened to a rigid steel light pole. After producing a wave pulse that was 5 mm high and 4 cm wide, you want to produce a pulse that is 4 cm wide but 7 mm high. You must move your hand up and down once,

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A sculptor strikes a piece of marble with a hammer. Find the speed of sound through the marble (in km/s). (The Young's modulus is 50 × 10⁹ N/m² and its density is 2.7 × 10³ kg/m³.)

The wavelength of light visible to the human eye is on the order of 5 × 10−⁷ m. If the speed of light in air is 3 × 10⁸ m/s, find the frequency of the lightwave.

The velocity of sound in sea water is 1.53 × 10³ m/s. Find the bulk modulus (in N/m²) of sea water if its density is 1.03 × 10³ kg/m³.

A jet plane has a sound level of 150 dB. What is the intensity in W/m²?

A point source emits sound with a power output of 100 watts. What is the intensity (in W/m²) at a distance of 10.0 m from the source?