Conceptual Physics Chapter 20

55) A piano tuner knows that a key on the piano is tuned to the frequency of his tuning fork when he strikes them at the same time and the number of beats he hears each second is A) 0. B) 1. C) 2. D) 3. E) 4.

A) 0.

40) A 340-hertz sound wave travels at 340 m/s in air with a wavelength of A) 1 m. B) 10 m. C) 100 m. D) 1000 m. E) None of the above choices are correct.

A) 1 m.

46) The beat frequency produced when a 240 hertz tuning fork and a 246 hertz tuning fork are sounded together is A) 6 hertz. B) 12 hertz. C) 240 hertz. D) 245 hertz. E) None of the above choices are correct.

A) 6 hertz.

31) Sound waves can interfere with one another so that no sound results. A) True B) False C) Either true or false, depending on the air temperature.

A) True

35) In the case of radio, which has the higher frequency? A) carrier wave B) sound wave C) Neither. Both may be of the same frequency.

A) carrier wave

36) For FM radio, the F stands for A) frequency. B) forced vibration at which resonance occurs. C) foul. D) female. E) fax.

A) frequency.

21) The energy of sound in air eventually becomes A) increased internal energy of the air. B) weaker and weaker until it disappears. C) cancelled by destructive interference. D) cancelled by both destructive and constructive interference.

A) increased internal energy of the air.

42) Resonance can be looked at as forced vibration with the A) least amount of energy input. B) maximum amount of energy input. C) matching of wave amplitudes. D) matching of constructive and destructive interference. E) minimum beat frequency.

A) least amount of energy input.

23) The wavelengths of sound that carry farther in air are relatively A) long. B) short. C) ultrasonic.

A) long.

7) A sound wave is a A) longitudinal wave. B) transverse wave. C) standing wave. D) shock wave. E) None of the above choices are correct.

A) longitudinal wave.

8) Compressions and rarefactions are characteristic of A) longitudinal waves. B) transverse waves. C) both longitudinal and transverse waves. D) none of the above.

A) longitudinal waves.

22) The frequencies of sound that carry farther in air are A) low. B) high. C) ultrasonic.

A) low.

47) A 1056-hertz tuning fork is sounded at the same time a piano note is struck. You hear three beats per second. What is the frequency of the piano string? A) not enough information to be certain B) 1056 hertz C) 1059 hertz D) 1053 hertz E) 3168 hertz

A) not enough information to be certain

26) The natural frequency of an object depends on its A) size, shape and elasticity. B) size and shape. C) size and elasticity. D) shape and elasticity.

A) size, shape and elasticity.

27) The object with the highest natural frequency is a A) small bell. B) large bell. C) medium size bell.

A) small bell.

9) Compressions and rarefactions normally travel in A) the same direction in a wave. B) opposite directions in a wave. C) directions that are at right angles to the wave direction.

A) the same direction in a wave.

17) When the speed of sound near the ground is greater than it is at higher altitudes, the sound tends to be bent A) upward. B) downward. C) to the left. D) to the right. E) None of the above choices are correct.

A) upward.

1) The source of every sound is something that is A) vibrating. B) moving. C) accelerating. D) undergoing simple harmonic motion. E) a net emitter of energy.

A) vibrating.

13) Sound travels faster in air if the air temperature is A) warm. B) cold. C) average.

A) warm.

3) Double the frequency of a sound and you halve its A) wavelength. B) speed. C) amplitude. D) all of these E) none of these

A) wavelength.

14) A wave having a frequency of 1000 hertz vibrates at A) less than 1000 cycles per second. B) 1000 cycles per second. C) more than 1000 cycles per second.

B) 1000 cycles per second.

5) The approximate range of human hearing is A) 10 hertz to 10,000 hertz. B) 20 hertz to 20,000 hertz. C) 40 hertz to 40,000 hertz. D) Actually all of these - depends on the hearing ability of the person.

B) 20 hertz to 20,000 hertz.

53) A general rule for estimating the distance in kilometers between an observer and a lightning bolt is to count the number of seconds between seeing the lightning and hearing it, and dividing by A) 2. B) 3. C) 4. D) 5. E) none of these

B) 3.

49) Which type of radio wave produces the least static in a radio receiver? A) AM B) FM C) Both have equal amounts of static.

B) FM

51) Xenon has atomic number 54, while Krypton has atomic number 36. Given that both gases are at the same temperature, in which medium does sound travel faster? A) Xenon gas B) Krypton gas C) a mixture of both gases D) the same in either gas

B) Krypton gas

28) The least energy required to produce forced vibration in an object occurs A) below its natural frequency. B) at its natural frequency. C) above its natural frequency.

B) at its natural frequency.

Figure 20-A 41) When the handle of a tuning fork is held solidly against a table, the sound becomes louder and the time that the fork keeps vibrating A) becomes longer. B) becomes shorter. C) remains the same.

B) becomes shorter.

Figure 20-B 50) Repeatedly tap the side of a drinking glass with a spoon while filling it with water and you will notice that the pitch of the sound A) increases. B) decreases. C) remains relatively constant.

B) decreases.

44) Inhaling helium increases the pitch of your voice. One reason for this is that sound travels A) slower in helium than in air. B) faster in helium than in air. C) the same speed in helium, but the wavelength is greater.

B) faster in helium than in air.

52) A neon atom has a larger atomic number than a helium atom. At the same temperature and pressure, how does the speed of sound in helium gas compare to the speed of sound in neon gas? A) greater in neon than in helium B) greater in helium than in neon C) the same in both gases D) depends on the frequency of the sound generated

B) greater in helium than in neon

34) When you tune a radio to a certain station, you match the frequency of the internal electrical circuit to the frequency of the wanted radio station. In so doing you are employing the principle of A) forced vibrations. B) resonance. C) beats. D) reverberation. E) wave interference.

B) resonance.

25) A base fiddle is louder than a harp because of its A) thicker strings. B) sounding board. C) lower pitch. D) All of the above are true. E) None of the above are true.

B) sounding board.

38) On some days, air nearest the ground is colder than air that is higher up. On one of these days, sound waves A) tend to be refracted upward. B) tend to be refracted downward. C) travel without refraction

B) tend to be refracted downward.

39) Sound refraction depends on the fact that the speed of sound is A) constant. B) variable. C) proportional to frequency. D) inversely proportional to wavelength. E) None of the above choices are correct.

B) variable.

24) Sound will be louder if a struck tuning fork is held A) in the air. B) with its base against a table top. C) with its prongs in shallow water. D) in your closed fist.

B) with its base against a table top.

37) For AM radio, the A stands for A) acceleration. B) authorized. C) amplitude. D) agony. E) almost.

C) amplitude.

18) Refraction of sound can occur in A) air. B) water. C) both air and water. D) neither air nor water.

C) both air and water.

19) A dolphin perceives its environment by the sense of A) sight. B) sound. C) both sight and sound. D) neither sight nor sound.

C) both sight and sound.

43) In which one of these media does sound travel the fastest? A) water vapor B) water C) ice D) steam E) Sound travels the same speed in each of the above media.

C) ice

32) The phenomenon of beats results from sound A) refraction. B) reflection. C) interference. D) all of these E) none of these

C) interference.

2) A sound source of high frequency emits a high A) speed. B) amplitude. C) pitch. D) all of these E) none of these

C) pitch.

33) Which doesn't belong to the same family? A) infrasonic waves B) ultrasonic waves C) radio waves D) shock waves E) longitudinal waves

C) radio waves

15) Reverberation is actually a case of A) sound interference. B) forced vibrations. C) re-echoed sound. D) resonance. E) none of the above

C) re-echoed sound.

16) The explanation for refraction must involve a change in A) frequency. B) wavelength. C) speed. D) All of the above choices are true. E) None of the above choices are true.

C) speed.

10) Sound travels faster in A) air. B) water. C) steel. D) a vacuum. E) Sound travels at about the same speed in all of the above media.

C) steel.

12) The speed of a sound wave in air depends on A) its frequency. B) its wavelength. C) the air temperature. D) All of the above choices are correct. E) None of the above choices are correct.

C) the air temperature.

54) Two tuning forks produce sounds of wavelengths 3.4 meters and 3.3 meters. Approximately what beat frequency is produced? A) 0.1 hertz B) 1.0 hertz C) 2.0 hertz D) 3.0 hertz E) 4.0 hertz

D) 3.0 hertz

20) In perceiving its environment, a dolphin makes use of A) echoes. B) the Doppler effect. C) ultrasound. D) All of the above choices are correct. E) None of the above choices are correct.

D) All of the above choices are correct.

6) We are best at hearing A) infrasonic sound. B) ultrasonic sound. C) both infrasonic and ultrasonic sounds. D) None of the above choices are true.

D) None of the above choices are true.

11) Sound waves cannot travel in A) air. B) water. C) steel. D) a vacuum. E) any of the above media

D) a vacuum.

29) Caruso is said to have made a crystal chandelier shatter with his voice. This is a demonstration of A) an echo. B) sound refraction. C) beats. D) resonance. E) interference.

D) resonance.

48) Suppose you sound a 1056-hertz tuning fork at the same time you strike a note on the piano and hear 2 beats/second. You tighten the piano string very slightly and now hear 3 beats/second. What is the frequency of the piano string? A) 1053 hertz B) 1054 hertz C) 1056 hertz D) 1058 hertz E) 1059 hertz

E) 1059 hertz

56) Longitudinal waves of different lengths are traveling though a long metal rod. Those that travel at the greatest speed are A) the shortest. B) those of medium length. C) the longest. D) impossible to predict without knowing the type of metal. E) None of the above choices are correct.

E) None of the above choices are correct.

45) An explosion occurs 34 km away. Since sound travels at 340 m/s, the time it takes for the sound to reach you is A) 0.1 second. B) 1 second. C) 10 seconds. D) 20 seconds. E) more than 20 seconds.

E) more than 20 seconds.

4) Double the frequency of sound and you also double its A) wavelength. B) speed. C) amplitude. D) all of these E) none of these

E) none of these

30) In designing a music hall, an acoustical engineer deals mainly with A) modulation. B) forced vibrations. C) resonance. D) beats. E) wave interference.

E) wave interference.