# Applying the Concepts Ch. 5

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b. Vibration.

b. Frequency.

c. Hertz.

d. Amplitude.

### 5. A wave with motion perpendicular to the direction that the wave is moving is classified as a a. Longitudinal wave. b. Transverse wave. c. Water wave. d. Compression wave.

b. Transverse wave.

c. Pitch.

### 7. Sound waves with frequencies greater than 20,000 Hz are a. Infrasonic waves. b. Supersonic waves. c. Ultrasonic waves. d. Impossible.

c. Ultrasonic waves.

a. Solids.

a. Warmer air.

c. Refraction.

### 11. A reflected sound that reaches the ear within 0.1 s after the original sound results in a. An echo. b. Reverberation. c. Refraction. d. Confusion.

b. Reverberation.

b. Cooler air.

### 13. Two in-phase sound waves with the same amplitude and frequency arrive at the same place at the same time, resulting in a. Higher frequency. b. Refraction. c. A new sound wave with greater amplitude. d. Reflection.

c. A new sound wave with greater amplitude.

### 14. Two out-of-phase sound waves with the same amplitude and frequency arrive at the same place at the same time, resulting in a. A beat. b. Cancellation of the two sound waves. c. A lower frequency. d. The bouncing of one wave.

b. Cancellation of the two sound waves.

### 15. Two sound waves of equal amplitude with slightly different frequencies will result in a. An echo. b. The Doppler Effect. c. Alternation of loudness of sound known as beats. d. Two separate sounds.

c. Alternation of loudness of sound known as beats.

### 16. Two sound waves of unequal amplitudes with different frequencies will result in a. An echo. b. The Doppler Effect. c. Alternation of loudness of sound known as beats. d. Two separate sounds.

d. Two separate sounds.

a. Intensity.

### 18. A decibel noise level of 40 would be most likely found a. During a calm day in the forest. b. On a typical day in the library. c. In heavy street traffic. d. Next to a pneumatic drill.

b. On a typical day in the library.

### 19. A resonant condition occurs when a. An external force matches a natural frequency. b. A beat is heard. c. Two out-of-phase waves have the same frequency. d. A pure tone is created.

a. An external force matches a natural frequency.

### 20. The fundamental frequency of a string is the a. Shortest wavelength harmonic possible on the string. b. Longest standing wave that can fit on a string. c. Highest frequency possible on the string. d. Shortest wavelength that can fit on the string.

b. Longest standing wave that can fit on a string.

b. 1/2

d. Overtones.

### 23. A moving source of sound or a moving observer experiences the apparent shift I frequency called a. Fundamental frequency. b. Doppler effect. c. Wave front effect. d. Shock waves.

b. Doppler effect.

### 24. Does the Doppler effect occur when the observer is moving and the source of sound is stationary? a. Yes, the effect is the same. b. No, the source must be moving. c. Yes, but the change of pitch effects is reversed in the case.

a. Yes, the effect is the same.

c. Mach 3.

### 26. A longitudinal mechanical wave causes particles of a material to move a. Back and forth in the same direction the wave is moving. b. Perpendicular to the direction the wave is moving. c. In a circular motion in the direction the wave is moving. d. In a circular motion opposite the direction the wave is moving.

a. Back and forth in the same direction the wave is moving.

### 27. A transverse mechanical wave cause particles of a material to move a. Back and forth in the same direction the wave is moving. b. Perpendicular to the direction the wave is moving. c. In a circular motion in the direction the wave is moving. d. In a circular motion opposite the direction the wave is moving.

b. Perpendicular to the direction the wave is moving.

a. Solids.

### 29. Longitudinal mechanical waves will move only through a. Solids. b. Liquids. c. Gases. d. All of the above are correct.

d. All of the above are correct.

### 30. A pulse of jammed-together molecules that quickly moves away from a vibration object. a. Is called a condensation. b. Causes an increased air pressure when it reaches an object. c. Has a greater density than the surrounding air. d. All of the above are correct.

d. All of the above are correct.

c. Frequency.

### 32. Sound waves travel faster in a. Solids as compared to liquids. b. Liquids as compared to gases. c. Warm air as compared to cooler air. d. All of the above are correct.

d. All of the above are correct.

### 33. The difference between an echo and a reverberation is a. An echo is a reflected sound; reverberation is not. b. The time interval between the original sound and the reflected sound. c. The amplitude of an echo is much greater. d. Reverberation comes from acoustical speakers; echoes come from cliffs and wills.

b. The time interval between the original sound and the reflected sound.

c. Beats.

### 35. The fundamental frequency of a standing wave on a string has a. One node and one antinode. b. One node and two antinodes. c. Two nodes and one antinode. d. Two nodes and two antinodes.

c. Two nodes and one antinode.

### 36. An observer on the ground will hear a sonic boom from an airplane traveling faster than the speed of sound a. Only when the plane breaks the sound barrier. b. As the plane is approaching. c. When the plane is directly overhead. d. After the plane has passed by.

d. After the plane has passed by.

### 37. What comment is true about the statement that "the human ear hears sounds originating from vibrating objects with a frequency between 20 and 20,000 Hz"? a. This is true only at room temperature. b. About 95 percent hear in this range, while some hear outside the average limits. c. This varies, with females hearing frequencies above 20,000 Hz. d. Very few people hear the whole range, which decreases with age.

d. Very few people hear the whole range, which decreases with age.

### 38. A sound wave the moves through the air is a. Actually a tiny sound that the ear magnifies. b. Pulses of increased and decreased air pressure. c. A transverse wave that carries information about a sound. d. A combination of longitudinal and transverse wave patterns.

b. Pulses of increased and decreased air pressure.

### 39. During a track and field meet, the time difference between seeing the smoke from a starter's gun and hearing the bang would be less a. On a warmer day. b. On a cooler day. c. If a more powerful shell were used. d. If a less powerful shell were used.

a. On a warmer day.

c. Amplitude

### 41. An airplane pilot hears a slow beat from the two engines of his plane. He increases the speed of the right engine and now hears a slower beat. What should the pilot now do to eliminate the beat? a. Increase the speed of the left engine. b. Decrease the speed of the right engine. c. Increase the speed of both engines. d. Increase the speed of the right engine.

d. Increase the speed of the right engine.

### 42. Resonance occurs when an external force matches the a. Interference frequency. b. Decibel frequency. c. Beat frequency. d. Natural frequency.

d. Natural frequency.

### 43. The sound quality is different for the same-pitch note produced by two different musical instruments, but you are able to recognize the basic note because of the some a. Harmonics. b. Fundamental frequency. c. Node positions. d. Standing waves.

b. Fundamental frequency.

### 44. What happens if the source of a sound is moving toward you at a high rate of speed? a. The sound will be traveling faster than from a stationary source. b. The sound will be moving faster only in the direction of travel. c. You will hear a higher frequency, but people in the source will not. d. All observers in all directions will hear a higher frequency.

c. You will hear a higher frequency, but people in the source will not.

### 45. What happens if you are moving at a high rate of speed toward some people standing next to a stationary source of a sound? You will hear a. A higher frequency than the people you are approaching will hear. b. The same frequency as the people you are approaching will hear. c. The same frequency as when you and the source are not moving. d. A higher frequency, as will all observers in all directions.

a. A higher frequency than the people you are approaching will hear.

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