Filters
Question type

Study Flashcards

A string under tension carries a transverse wave traveling at speed v. If the tension in the string is halved and the linear density of the string is quadrupled, what is the wave speed?


A) The wave speed is unchanged.
B) The wave speed is halved.
C) The wave speed is quadrupled.
D) The wave speed decreases to about 71% of v.
E) The wave speed increases by about 41%.

F) All of the above
G) A) and D)

Correct Answer

verifed

verified

An observer is standing on the platform of a railway station. A train goes through the station without stopping. If the frequency of the train whistle decreases by a factor of 1.2 as it approaches and then passes him, calculate the speed of the train (assume the speed of sound in air = 343 m/s) .


A) 112 km/hr
B) 31.2 km/hr
C) 56.0 km/hr
D) 62.0 km/hr
E) 122 km/hr

F) A) and C)
G) C) and D)

Correct Answer

verifed

verified

You are in a park when you spot your friend 100 m away. At what lowest decibel should you shout your greetings so that your friend can just hear you? Assume that your friend has normal hearing.


A) 30 dB
B) 40 dB
C) 50 dB
D) 60dB
E) 70 dB

F) B) and D)
G) B) and C)

Correct Answer

verifed

verified

A police car siren emits a sound at 600 Hz. If observer A moves toward the source at 50 km/hr, and the police car is traveling toward observer A at 100 km/hr (all speeds relative to the road) , calculate the siren frequency heard by the observer A (assume the speed of sound in air = 343 m/s) .


A) 626 Hz
B) 600 Hz
C) 679 Hz
D) 577 Hz
E) 970 Hz

F) A) and C)
G) B) and E)

Correct Answer

verifed

verified

The power transmitted by any harmonic wave varies directly as


A) the period.
B) the square root of the frequency.
C) the amplitude.
D) the amplitude squared.
E) None of these is correct.

F) A) and D)
G) B) and D)

Correct Answer

verifed

verified

If you were to double the speed of a wave on a string while keeping the frequency and amplitude of the wave constant, the rate at which energy is delivered by the wave would


A) double.
B) quadruple.
C) be reduced 50%.
D) be reduced to 25% of its previous value.
E) be unchanged.

F) C) and E)
G) A) and E)

Correct Answer

verifed

verified

A jet engine emits a whine of frequency 3000 Hz. When the engine is moving directly away from an observer at half the speed of sound, an observer hears a frequency of


A) 1000 Hz
B) 1500 Hz
C) 2000 Hz
D) 4500 Hz
E) 6000 Hz

F) B) and C)
G) C) and E)

Correct Answer

verifed

verified

  A pulse moves in a string toward a free end (a ring on a post)  as indicated in the sketch. On reflection, the pulse would most nearly be represented by A)  1 B)  2 C)  3 D)  4 E)  5 A pulse moves in a string toward a free end (a ring on a post) as indicated in the sketch. On reflection, the pulse would most nearly be represented by


A) 1
B) 2
C) 3
D) 4
E) 5

F) A) and B)
G) A) and C)

Correct Answer

verifed

verified

Which curve best illustrates the variation of wave velocity with tension in a vibrating string? Which curve best illustrates the variation of wave velocity with tension in a vibrating string?   A)  1 B)  2 C)  3 D)  4 E)  5


A) 1
B) 2
C) 3
D) 4
E) 5

F) A) and D)
G) A) and E)

Correct Answer

verifed

verified

Both particles and waves transfer energy from one location to another. Which of the following statements is true?


A) Both methods of energy transfer follow the conservation of energy principle.
B) Energy transfer by particles follows the conservation of energy principle but waves do not.
C) Energy transfer by waves follows the conservation of energy principle but particles do not.
D) Whether the transfer of energy by a wave follows the conservation of energy principle depends on the speed of the wave.
E) Whether the transfer of energy by a particle follows the conservation of energy principle depends on the speed of the particle.

F) B) and C)
G) A) and E)

Correct Answer

verifed

verified

Use the following scenario to answer the next question. A rope of length L and linear mass density μ\mu is tied to the ceiling on one end. The other end is tied to a spring with spring constant k, and the spring is then attached to the floor, extending it by A. -The tension of the rope at height y from the spring is


A) kA
B) μ\mu gy
C) μ\mu gy + kA
D) μ\mu gy - kA
E) kA - μ\mu gy

F) C) and D)
G) D) and E)

Correct Answer

verifed

verified

Sound travels at 340 m/s in air and 1500 m/s in water. A sound of 256 Hz is made under water. In the air,


A) the frequency remains the same but the wavelength is shorter.
B) the frequency is higher but the wavelength stays the same.
C) the frequency is lower but the wavelength is longer.
D) the frequency is lower and the wavelength is shorter.
E) both the frequency and the wavelength remain the same.

F) A) and C)
G) B) and C)

Correct Answer

verifed

verified

If a sound of intensity I = 1.0 ×\times 10-6 W/m2 falls on a detector of area A = 7.0 ×\times 10-5 m2 (about the size of your eardrum) , how much power is received by the detector?


A) 6.2 ×\times 10-14 W
B) 1.0 ×\times 10-6 W
C) 7.0 ×\times 10-11 W
D) 1.4 ×\times 10-2 W
E) 70 W

F) C) and E)
G) All of the above

Correct Answer

verifed

verified

To double the rate at which energy is transmitted along a string, you could


A) double the angular frequency of the source.
B) double the amplitude of the wave.
C) double the tension in the string.
D) quadruple the tension in the string.
E) halve the linear density of the string.

F) A) and B)
G) C) and D)

Correct Answer

verifed

verified

The equation of a traveling wave is Y(x, t) = 0.02 cos(0.25x - 500t) Where the units are SI. The velocity of the wave is


A) 4.0 m/s
B) 10 m/s
C) 0.13 km/s
D) 0.50 km/s
E) 2.0 km/s

F) D) and E)
G) B) and E)

Correct Answer

verifed

verified

The sound level of a dog's bark is 50 dB. The intensity of a rock concert is 10,000 times that of the dog's bark. What is the sound level of the rock concert?


A) 10,050 dB
B) 500,000 dB
C) 90 dB
D) 2000 dB
E) 54 dB

F) A) and B)
G) A) and C)

Correct Answer

verifed

verified

The human ear can be sensitive to sound frequencies up to 20 kHz. What wavelength does this correspond to at normal temperature and pressure?


A) 0.165 m
B) 165 cm
C) 16.5 mm
D) 1650 ×\times 10-4 m
E) 1.65 mm

F) A) and D)
G) B) and D)

Correct Answer

verifed

verified

Workmen are digging up the road using pneumatic tools. If a single tool creates a noise level of 88 decibels a few meters away, calculate the noise level if four such tools were in operation the same distance away.


A) 176 dB
B) 90 dB
C) 352 dB
D) 94 dB
E) 92 dB

F) A) and E)
G) C) and D)

Correct Answer

verifed

verified

Two sounds differ by 30 dB. The intensity of the louder sound IL, compared with the softer IS, is IL/IS. The value of the ratio is


A) 1000
B) 30
C) 9
D) 100
E) 300

F) A) and E)
G) A) and D)

Correct Answer

verifed

verified

Two sounds differ by 20 dB. This means that the louder sound is _____ times as intense and _____ times as loud.


A) twenty; twenty
B) one hundred; twenty
C) twenty; four
D) one hundred; four
E) two; two

F) A) and B)
G) D) and E)

Correct Answer

verifed

verified

Showing 101 - 120 of 122

Related Exams

Show Answer