Wave quiz review
1) An alien is able to stand on the surface of the moon without a life support system. Will he or she be
able to hear an explosion? Why or Why not?
No. There is no air on the moon and hence, no medium through which a sound wave could travel.
2) In a science fiction movie a space ship explodes killing all the evil aliens. Unfortunately, the intense
sound waves from the explosion rattle the hero’s ship and kill him as well. Why should the science
advisor to the film be fired?
(Assuming that this occurs in space) there is no air and hence, no medium through which a sound
wave could travel.
3) The frequency of a sound is increased. What has happened to the: wavelength, wave velocity, and
amplitude of the wave?
Wavelength is decreased. Velocity and amplitude are unaffected.
4) Watching the Fourth of July fireworks from a field near the Pentagon, Deborah measures the delay
time between seeing the fireworks and hearing them is 1.2 s. How far away is Deborah from the
explosions?
(assuming a temperature of 20°C – sorry about the omission) – 412m
TRUE or FALSE: Identify the following statements as being either true (T) or false (F).T or F? For those
that are false, explain WHY!
1.
T
Waves are created by a vibration.
2.
F
As a wave moves through a medium, the individual particles of the medium move from
the source of the wave to another location some distance away.
3.
T
Waves are a means of transporting energy from one location to another without actually
displacing matter from one location to another.
4.
F
An ocean wave will transport ocean water from near the middle of the
a location near the shore.
ocean to
5.
6.
7.
8.
T
As mechanical waves move through a medium, particles of the medium undergo a
periodic and repeated vibration about a fixed position.
T
Sound waves are longitudinal waves.
F
As the teacher talks, students hear the voice because particles of air move from the
mouth of the teacher to the ear of the student.
T
All sound waves are produced by a vibrating object.
9. Mechanical waves propagate or move through a medium because ___b_____.
a. the particles of the medium are able to move along the curved wavelike pathway
b. one particle pushes or pulls on the adjacent particle which pushes or pulls on the next
particle which ...
c. the initial vibration of the medium causes the medium to assume the wavelike shape and
this shape subsequently moves from one location to another.
10. The arrows on the diagrams below represent the direction of particle motion.
Diagram A shows a __ transverse __ pulse and diagram B shows a __ longitudinal __ pulse.
11. Compare the direction in which particles of the medium vibrate for a longitudinal wave compared to
a transverse wave
Transverse – perpendicular to direction of wave travel
longitudinal – parallel to direction of wave travel
12. A pendulum makes 40 vibrations in 20 seconds. Calculate its period. 0.5 sec
13. A child accompanies her father to the park for an afternoon of fun. While there, she hops on the
swing and begins a motion characterized by a complete back-and-forth cycle every 5.0 seconds.
What is the frequency of the child’s swing?
0.2 cycles per sec
14. A period of 5.0 seconds corresponds to a frequency of ___0.2__ Hz.
15. The period of a 261 Hertz sound wave is ______0.004 sec__________.
16. As the frequency of a wave increases, the period of the wave _____a______.
a. decreases
b. increases
c. remains the same
17. The speed of a wave refers to
a. how often it vibrates to and fro.
b. how high it vibrates.
c. how much time it takes to vibrate to and fro.
d. how far a given point (e.g., a crest) on the wave travels per unit of time.
18. A fisherman uses a sonic ranger to determine the depth of a lake. The sound waves travel at 1210
m/s through the water and require 0.020 seconds to travel to the lake's bottom and back to the
boat. How deep is the lake?
12.1 m
19. The water waves below are traveling with a speed of 3.0 m/s and splashing periodically against
Wilbert's perch. Each adjacent crest is 6.0 meters apart and splashes Wilbert's feet upon reaching
his perch. How much time passes between each successive drenching? Explain your answer.
2 sec
20. A physics teacher attaches a slinky to the wall and begins introducing pulses with different
amplitude. Which of the two pulses below will take the least amount of time to reach the wall?
Justify your answer:
They will be the same. Wave velocity is determined ONLY by properties of the medium.
21. What is the speed of a wave which has a frequency of 200 Hz and a wavelength of 0.50 m?
100 m/s
22. The period of a wave is 0.0300 seconds. It travels at a velocity of 10.0 m/s. Determine the frequency
and the wavelength of the wave.
0.3 m
23. Match the following wave quantities to the mini-definition. Place the letter in the blank.
A. Frequency B. Period
1.
2.
3.
4. B
5. E
C
D
A
C. Speed D. Wavelength E. Amplitude
How fast the wave moves through the medium.
How long the wave is.
How often the particles vibrate about their fixed position.
How much time it takes the particles to complete a vibrational cycle.
How far the particles vibrate away from their resting position.
24. The speed of a sound wave depends upon the ___d___.
a. frequency of the wave
c. amplitude of the wave
b. wavelength of the wave
d. properties of the medium through which it moves
25. If a person yells (as opposed to whispering), then it will cause __c____.
a. air molecules to vibrate more frequently
b. the sound wave to travel faster
c. air molecules to vibrate with a greater amplitude
26. Miles Tugo is camping in Glacier National Park. In the midst of a glacier canyon, he makes a loud
holler. The sound (v = 345 m/s) bounces off the nearest canyon wall (which is located 170 meters
away from Miles) and returns to Miles. Determine the time elapsed between when Miles makes the
holler and the echo is heard.
0.99 sec (think about the echo)