Question 1

A wave moves at a constant speed along a string. Which one of the following statements is false concerning the motion of particles in the string?

Accepted Answer

A) The particle speed is constant. 
B) The particle speed is not the same as the wave speed. 
C) The particle speed depends on the amplitude of the periodic motion of the source. 
D) The particle speed depends on the frequency of the periodic motion of the source. 
E) The particle speed is independent of the tension and linear density of the string.

Question 2

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. 
-What is the frequency of the wave?

Accepted Answer

A) 0.60 Hz 
B) 0.90 Hz 
C) 1.1 Hz 
D) 1.3 Hz 
E) 1.7 Hz

Question 3

The intensity of a spherical wave 2.5 m from the source is 120 W/m2. What is the intensity at a point 9.0 m away from the source?

Accepted Answer

A) 9.3 W/m2 
B) 24 W/m2 
C) 53 W/m2 
D) 80 W/m2 
E) 270 W/m2

Question 4

When one person was talking in a small room, the sound intensity level was 60 dB everywhere within the room. Then, there were 14 people talking in similar manner simultaneously in the room, what was the resulting sound intensity level?

Accepted Answer

A) 60 dB 
B) 79 dB 
C) 71 dB 
D) 64 dB 
E) 69 dB

Question 5

The speed of sound in a certain metal block is 2.00 × 103 m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds). What is the wavelength of this wave?

Accepted Answer

A) 0.5 m 
B) 1.5 m 
C) 3.0 m 
D) 4.0 m 
E) 6.0 m

Question 6

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. 
-What is the amplitude of the wave?

Accepted Answer

A) 2 mm 
B) 4 mm 
C) 8 mm 
D) 12 mm 
E) 16 mm

Question 7

A wave has an amplitude of 0.35 m, a frequency of 1.05 × 106 Hz, and travels in the positive x direction at the speed of light, 3.00 × 108 m/s. Which one of the following equations correctly represents this wave?

Accepted Answer

A) y = 0.35 sin (6.60 × 106t - 0.022x) 
B) y = 0.35 sin (6.60 × 106t + 0.022x) 
C) y = 0.35 sin (286t - 1.05 × 106x) 
D) y = 0.35 sin (286t + 1.05 × 106x) 
E) y = 0.35 sin (1.05 × 106t + 3.00 × 108x)

Question 8

A transverse wave is traveling in the -x direction on a string that has a linear density of 0.011 kg/m. The tension in the string is 7.4 N. The amplitude of the wave is 0.017 m; and its wavelength is 1.5 m. Which one of the following is the correct equation for the displacement of a particle from its equilibrium position?

Accepted Answer

A) y = (0.017 m)sin[(84 Hz)t + (4.2 m-1)x] 
B) y = (0.017 m)sin[(110 Hz)t + (4.2 m-1)x] 
C) y = (4.2 m)sin[(84 Hz)t + (59 m-1)x] 
D) y = (4.2 m)sin[(110 Hz)t - (59 m-1)x] 
E) y = (0.017 m)sin[(110 Hz)t - (8.4 m-1)x]

Question 9

Which one of the following waves is purely longitudinal?

Accepted Answer

A) sound waves in air 
B) microwaves traveling through air 
C) radio waves traveling through vacuum 
D) waves on a plucked violin string 
E) surface waves in a shallow pan of water

Question 10

A steel wire of mass 0.400 kg and length 0.640 m supports a 102-kg block. The wire is struck exactly at its midpoint causing a small displacement. How long does it take the peak of this displacement to reach the top of the wire?

Accepted Answer

A) 2.00 × 10-3 s 
B) 4.00 × 10-3 s 
C) 6.00 × 10-3 s 
D) 8.00 × 10-3 s 
E) 1.60 × 10-2 s

Question 11

A source moving through water at 10.0 m/s generates water waves with a frequency of 5.0 Hz. The speed of these water waves relative to the water surface is 20.0 m/s. The source approaches an observer who is at rest in the water. What wavelength would be measured for these waves by the stationary observer?

Accepted Answer

A) 1.0 m 
B) 2.0 m 
C) 4.0 m 
D) 6.0 m 
E) 8.0 m

Question 12

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s.
-How could the speed of the wave be increased?

Accepted Answer

A) by increasing the period 
B) by decreasing the amplitude 
C) by decreasing the frequency 
D) by increasing the tension in the string 
E) by increasing amplitude

Question 13

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. 
-What is the difference in phase between the points A and B?

Accepted Answer

A) ($\pi$/4)radians 
B) ($\pi$/2)radians 
C) $\pi$radians 
D) (3$\pi$/4)radians 
E) 2$\pi$ radians

Question 14

The Young's modulus of aluminum (density = 2700 kg/m3) is 6.9 × 1010 N/m2. Determine the speed of sound in an aluminum rod.

Accepted Answer

A) 1.4 × 103 m/s 
B) 2.5 × 103 m/s 
C) 5.1 × 103 m/s 
D) 6.3 × 103 m/s 
E) 7.0 × 103 m/s

Question 15

The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. 
-At which position(s) will the child hear the lowest frequency for the sound from the whistle?

Accepted Answer

A) at both A and D 
B) at B when moving toward A 
C) at B when moving toward C 
D) at C when moving toward B 
E) at C when moving toward D

Question 16

A periodic traveling wave is generated on a string of linear density 8.0 × 10-4 kg/m. Figure A shows the displacements of the particles in the string as a function of the position x along the string at t = 0 s. Figure B shows the displacement of the particle at x = 0 m as a function of time. The particle positions are measured from the left end of the string (x = 0 m) and the wave pulses move to the right. 
-What is the wavelength of the wave?

Accepted Answer

A) 0.005 m 
B) 0.010 m 
C) 0.015 m 
D) 0.020 m 
E) 0.025 m

Question 17

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s.
-What is the frequency of the wave?

Accepted Answer

A) 0.67 Hz 
B) 1.33 Hz 
C) 13 Hz 
D) 30 Hz 
E) 57 Hz

Question 18

The car in the drawing is moving to the left at 35 m/s. The car's horn continuously emits a 2.20 × 102 Hz sound. The figure also shows the first two regions of compression of the emitted sound waves. The speed of sound is 343 m/s. 
-What is the wavelength of the sound in the direction of motion of the car?

Accepted Answer

A) 1.40 m 
B) 1.56 m 
C) 1.70 m 
D) 1.93 m 
E) 35 m

Question 19

A stationary railroad whistle is sounded. An echo is heard 5.0 seconds later by the train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface?

Accepted Answer

A) 68 m 
B) 140 m 
C) 860 m 
D) 1700 m 
E) 2000 m

Question 20

Two children setup a "telephone" by placing a long, slender aluminum (Y = 6.9 × 1010 N/m2) rod that has a length of 6.1-m between their two houses. To communicate, a child taps a coded message on one end. How long do the sound waves take to reach the other end? Note: the density of aluminum is 2700 kg/m3.

Accepted Answer

A) 1.2 × 10-3 s 
B) 2.4 × 10-7 s 
C) 8.0 × 10-6 s 
D) 6.3 × 10-5 s 
E) 1.1 × 10-4 s

Exam 16: Waves and Sound

A wave moves at a constant speed along a string. Which one of the following statements is false concerning the motion of particles in the string?

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. -What is the frequency of the wave?

The intensity of a spherical wave 2.5 m from the source is 120 W/m². What is the intensity at a point 9.0 m away from the source?

When one person was talking in a small room, the sound intensity level was 60 dB everywhere within the room. Then, there were 14 people talking in similar manner simultaneously in the room, what was the resulting sound intensity level?

The speed of sound in a certain metal block is 2.00 × 10³ m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds) . What is the wavelength of this wave?

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. -What is the amplitude of the wave?

A wave has an amplitude of 0.35 m, a frequency of 1.05 × 10⁶ Hz, and travels in the positive x direction at the speed of light, 3.00 × 10⁸ m/s. Which one of the following equations correctly represents this wave?

Which one of the following waves is purely longitudinal?

A steel wire of mass 0.400 kg and length 0.640 m supports a 102-kg block. The wire is struck exactly at its midpoint causing a small displacement. How long does it take the peak of this displacement to reach the top of the wire?

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s. -How could the speed of the wave be increased?

The Young's modulus of aluminum (density = 2700 kg/m³) is 6.9 × 10¹⁰ N/m². Determine the speed of sound in an aluminum rod.

The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. -At which position(s) will the child hear the lowest frequency for the sound from the whistle?

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s. -What is the frequency of the wave?

A stationary railroad whistle is sounded. An echo is heard 5.0 seconds later by the train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface?

Exam 16: Waves and Sound

A wave moves at a constant speed along a string. Which one of the following statements is false concerning the motion of particles in the string?

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. -What is the frequency of the wave?

The intensity of a spherical wave 2.5 m from the source is 120 W/m2. What is the intensity at a point 9.0 m away from the source?

When one person was talking in a small room, the sound intensity level was 60 dB everywhere within the room. Then, there were 14 people talking in similar manner simultaneously in the room, what was the resulting sound intensity level?

The speed of sound in a certain metal block is 2.00 × 103 m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds) . What is the wavelength of this wave?

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. -What is the amplitude of the wave?

A wave has an amplitude of 0.35 m, a frequency of 1.05 × 106 Hz, and travels in the positive x direction at the speed of light, 3.00 × 108 m/s. Which one of the following equations correctly represents this wave?

Which one of the following waves is purely longitudinal?

A steel wire of mass 0.400 kg and length 0.640 m supports a 102-kg block. The wire is struck exactly at its midpoint causing a small displacement. How long does it take the peak of this displacement to reach the top of the wire?

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s. -How could the speed of the wave be increased?

The displacement of a vibrating string versus position along the string is shown in the figure. The periodic waves have a speed of 10.0 cm/s. A and B are two points on the string. -What is the difference in phase between the points A and B?

The Young's modulus of aluminum (density = 2700 kg/m3) is 6.9 × 1010 N/m2. Determine the speed of sound in an aluminum rod.

The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. -At which position(s) will the child hear the lowest frequency for the sound from the whistle?

A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s. -What is the frequency of the wave?

A stationary railroad whistle is sounded. An echo is heard 5.0 seconds later by the train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface?

The intensity of a spherical wave 2.5 m from the source is 120 W/m². What is the intensity at a point 9.0 m away from the source?

The speed of sound in a certain metal block is 2.00 × 10³ m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds) . What is the wavelength of this wave?

A wave has an amplitude of 0.35 m, a frequency of 1.05 × 10⁶ Hz, and travels in the positive x direction at the speed of light, 3.00 × 10⁸ m/s. Which one of the following equations correctly represents this wave?

The Young's modulus of aluminum (density = 2700 kg/m³) is 6.9 × 10¹⁰ N/m². Determine the speed of sound in an aluminum rod.