Question 1

A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10-12 W/m2. What is the sound intensity level 30.0 m from the source?

Accepted Answer

A)   92.5 dB
B)   81.5 dB
C)   1.77 × 10-3 dB
D)   1.77 × 10-3 W
E)   -27.5 dB A

Question 2

Calculate the light intensity 1.51 m from a light bulb that emits 100 W of visible light, assuming that the light radiates uniformly in all directions.

Accepted Answer

A)   3.49 W/m2
B)   4.01 W/m2
C)   43.9 W/m2
D)   50.5 W/m2 A

Question 3

A plane flies toward a stationary siren at 1/4 the speed of sound. Then the plane stands still on the ground and the siren is driven toward it at 1/4 the speed of sound. In both cases, a person sitting in the plane will hear the same frequency of sound from the siren.

Accepted Answer

A) True 
 B)False  False

Question 4

A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400.00 Hz. The sound he hears reflected back from the wall is at a frequency 408.00 Hz. At what is the speed is the boy riding his bicycle toward the wall? Assume the speed of sound in air is 340 m/s.

Accepted Answer

A)   3.68 m/s
B)   333 m/s
C)   6.67 m/s
D)   6.80 m/s
E)   3.37 m/s

Question 5

The intensity of sunlight falling on the earth is about 1.4 kW/m2 (before any gets absorbed by our atmosphere). At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 108 km and the earth's radius = 6.4 × 103 km.)

Accepted Answer

A)   4.0 × 1026 W
B)   3.2 × 1022 W
C)   7.2 × 1014 W
D)   7.6 × 108 W

Question 6

A carousel that is 5.00 m in radius has a pair of 600-Hz sirens mounted on posts at opposite ends of a diameter. The carousel rotates with an angular velocity of 0.800 rad/s. A stationary listener is located at a distance from the carousel. The speed of sound is 350 m/s. The longest wavelength reaching the listener from the sirens is closest to

Accepted Answer

A)   57.0 cm.
B)   57.7 cm.
C)   58.3 cm.
D)   59.0 cm.
E)   59.6 cm.

Question 7

A transverse wave is traveling on a string stretched along the horizontal x-axis. The equation for the vertical displacement y of the string is given by y = 0.0020 cos[π(15x - 52t)], where all quantities are in SI units. The maximum speed of a particle of the string is closest to

Accepted Answer

A)   0.33 m/s.
B)   0.43 m/s.
C)   0.53 m/s.
D)   0.64 m/s.
E)   0.74 m/s.

Question 8

The figure shows the displacement y of a wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the frequency of the wave.

Accepted Answer

A)   4.0 Hz
B)   0.50 Hz
C)   3.0 Hz
D)   0.33 Hz
E)   0.25 Hz

Question 9

The density of aluminum is 2700 kg/m3. If transverse waves propagate at 34 ,s in a 4.6-mm diameter aluminum wire, what is the tension on the wire?

Accepted Answer

A)   52 N
B)   31 N
C)   42 N
D)   62 N

Question 10

For the wave shown in the figure, the frequency is

Accepted Answer

A)   0.5 Hz.
B)   1 Hz.
C)   2 Hz.
D)   4 Hz.
E)   unable to be determined from the given information.

Question 11

Ocean tides are waves that have a period of 12 hours, an amplitude (in some places) of 1.50 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves?

Accepted Answer

A)   9000 km
B)   32,400 km
C)   9000 m
D)   32,400 m
E)   2500 m

Question 12

If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d?

Accepted Answer

A)   146 dB
B)   89 dB
C)   5320 dB
D)   76 dB
E)   82 dB

Question 13

At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10-12 W/m2.

Accepted Answer

A)   77.0 dB
B)   74.0 dB
C)   60.0 dB
D)   40.0 dB
E)   20.0 dB

Question 14

For the wave shown in the figure, the wavelength is

Accepted Answer

A)   8 m.
B)   4 m.
C)   2 m.
D)   1 m.
E)   unable to be determined from the given information.

Question 15

The vertical displacement y(x,t) of a string stretched along the horizontal x-axis is given by y(x,t) = (6.00 mm) cos[(3.25 m^-1)x - (7.22 rad/s)t]. (a) What is the minimum time for each complete cycle of the wave? (b) What is the distance between adjacent crests of the wave? (c) How fast does this wave travel?

Accepted Answer

The answer of The vertical displacement y(x,t) of a string...

Question 16

A factory siren indicating the end of a shift has a frequency of 90.0 Hz. The speed of sound is 343 m/s.
(a) What frequency is perceived by the occupant of a car traveling towards the factory at 25.0 m/s?
(b) What frequency is perceived by the occupant of a car traveling away from the factory at 30.0 m/s?

Accepted Answer

The answer of A factory siren indicating the end of...

Question 17

In the figure, which of the curves best represents the variation of wave speed as a function of tension for transverse waves on a stretched string?

Accepted Answer

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

Question 18

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the wavelength of the wave.

Accepted Answer

A)   2.0 cm
B)   3.0 m
C)   2.0 m
D)   4.0 m
E)   1.5 m

Question 19

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. How fast is the wave traveling?

Accepted Answer

A)   3.0 m/s
B)   0.75 m/s
C)   0.66 m/s
D)   1.5 m/s
E)   2.0 m/s

Question 20

A transverse wave traveling along a string transports energy at a rate r. If we want to double this rate, we could

Accepted Answer

A)   increase the amplitude of the wave by a factor of 8.
B)   increase the amplitude of the wave by a factor of 4.
C)   increase the amplitude of the wave by a factor of 2.
D)   increase the amplitude by a factor of  .
E)   increase the amplitude by a factor of  .

Exam 20: Traveling Waves

A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10^-12 W/m². What is the sound intensity level 30.0 m from the source?

Calculate the light intensity 1.51 m from a light bulb that emits 100 W of visible light, assuming that the light radiates uniformly in all directions.

A plane flies toward a stationary siren at 1/4 the speed of sound. Then the plane stands still on the ground and the siren is driven toward it at 1/4 the speed of sound. In both cases, a person sitting in the plane will hear the same frequency of sound from the siren.

A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400.00 Hz. The sound he hears reflected back from the wall is at a frequency 408.00 Hz. At what is the speed is the boy riding his bicycle toward the wall? Assume the speed of sound in air is 340 m/s.

The intensity of sunlight falling on the earth is about 1.4 kW/m² (before any gets absorbed by our atmosphere) . At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 10⁸ km and the earth's radius = 6.4 × 10³ km.)

A transverse wave is traveling on a string stretched along the horizontal x-axis. The equation for the vertical displacement y of the string is given by y = 0.0020 cos[π(15x - 52t) ], where all quantities are in SI units. The maximum speed of a particle of the string is closest to

The figure shows the displacement y of a wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the frequency of the wave.

The density of aluminum is 2700 kg/m³. If transverse waves propagate at 34 ,s in a 4.6-mm diameter aluminum wire, what is the tension on the wire?

For the wave shown in the figure, the frequency is

Ocean tides are waves that have a period of 12 hours, an amplitude (in some places) of 1.50 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves?

If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d?

At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10^-12 W/m².

For the wave shown in the figure, the wavelength is

In the figure, which of the curves best represents the variation of wave speed as a function of tension for transverse waves on a stretched string?

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the wavelength of the wave.

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. How fast is the wave traveling?

A transverse wave traveling along a string transports energy at a rate r. If we want to double this rate, we could

Exam 20: Traveling Waves

A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10-12 W/m2. What is the sound intensity level 30.0 m from the source?

Calculate the light intensity 1.51 m from a light bulb that emits 100 W of visible light, assuming that the light radiates uniformly in all directions.

A plane flies toward a stationary siren at 1/4 the speed of sound. Then the plane stands still on the ground and the siren is driven toward it at 1/4 the speed of sound. In both cases, a person sitting in the plane will hear the same frequency of sound from the siren.

A boy on a bicycle approaches a brick wall as he sounds his horn at a frequency 400.00 Hz. The sound he hears reflected back from the wall is at a frequency 408.00 Hz. At what is the speed is the boy riding his bicycle toward the wall? Assume the speed of sound in air is 340 m/s.

The intensity of sunlight falling on the earth is about 1.4 kW/m2 (before any gets absorbed by our atmosphere) . At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 108 km and the earth's radius = 6.4 × 103 km.)

A transverse wave is traveling on a string stretched along the horizontal x-axis. The equation for the vertical displacement y of the string is given by y = 0.0020 cos[π(15x - 52t) ], where all quantities are in SI units. The maximum speed of a particle of the string is closest to

The figure shows the displacement y of a wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the frequency of the wave.

The density of aluminum is 2700 kg/m3. If transverse waves propagate at 34 ,s in a 4.6-mm diameter aluminum wire, what is the tension on the wire?

For the wave shown in the figure, the frequency is

Ocean tides are waves that have a period of 12 hours, an amplitude (in some places) of 1.50 m, and a speed of 750 km/hr. What is the distance between adjacent crests of these waves?

If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d?

At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10-12 W/m2.

For the wave shown in the figure, the wavelength is

In the figure, which of the curves best represents the variation of wave speed as a function of tension for transverse waves on a stretched string?

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. Determine the wavelength of the wave.

The figure shows the displacement y of a traveling wave at a given position as a function of time and the displacement of the same wave at a given time as a function of position. How fast is the wave traveling?

A transverse wave traveling along a string transports energy at a rate r. If we want to double this rate, we could

A sound source emits 20.0 W of acoustical power spread equally in all directions. The threshold of hearing is 1.0 × 10^-12 W/m². What is the sound intensity level 30.0 m from the source?

The intensity of sunlight falling on the earth is about 1.4 kW/m² (before any gets absorbed by our atmosphere) . At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 10⁸ km and the earth's radius = 6.4 × 10³ km.)

The density of aluminum is 2700 kg/m³. If transverse waves propagate at 34 ,s in a 4.6-mm diameter aluminum wire, what is the tension on the wire?

At a distance of 2.00 m from a point source of sound, the intensity level is 80.0 dB. What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10^-12 W/m².