Review Vibrations, Waves, and Sound

Review class lectures, notes, three pendulum experiments, and problem sheets. Be able to define key terms:

amplitude

antinodes

blue shift

bow wave

constructive interference

crest

destructive interference

Doppler effect

frequency

hertz

in phase

interference

longitudinal wave

node

out of phase

period

red shift

shock wave

simple harmonic motion

sine curve

sonic boom

standing wave

transverse wave

trough

vibration

wave

wavelength

Review Questions

1. What is the period of a pendulum?

2. Suppose that a pendulum has a period of 1.5 seconds. How long does it take to make a complete back-and-forth vibration? Is this 1.5-second period pendulum longer or shorter in length than a 1-second period pendulum?

5. How is a sine curve related to a wave?

6. Distinguish among these different parts of a wave: amplitude, crest, trough, and wavelength.

7. Distinguish between the period and the frequency of a vibration or a wave. How do they relate to one another?

8. Does the medium in which a wave travels move along with the wave itself? Defend your answer.

9. How does the speed of a wave relate to its wavelength and frequency?

10. As the frequency of sound is increased, does the wavelength increase or decrease? Give an example.

11. Distinguish between a transverse wave and a longitudinal wave.)

12. Distinguish between constructive interference and destructive interference.

13. When a wave source moves toward a receiver, does the receiver encounter an increase in wave frequency, wave speed, or both?

14. What is a sonic boom?

15. How fast must an aircraft fly in order to produce a sonic boom?

16. If you triple the frequency of a vibrating object, what will happen to its period?

17. How far, in terms of wavelength, does a wave travel in one period?

18. If a wave vibrates up and down twice each second and travels a distance of 20 m each second, what is its frequency? Its wave speed?

19. Astronomers find that light coming from point A at the edge of the sun has a slightly higher frequency than light from point B at the opposite side. What do these measurements tell us about the sun's motion?

20. Whenever you watch a high-flying aircraft overhead, it seems that its sound comes from behind the craft rather than from where you see it. Why is this?

21. As a supersonic aircraft gains speed, does the conical angle of its shock wave become wider, narrower, or remain constant?

22. Why is it that a subsonic aircraft, no matter how loud it may be, cannot produce a sonic boom?