Name _________________________________ Period______ Date ______________
Homework packet on Waves
Thursday's homework
Copy the following definitions from the last page of this handout into the spaces here:
1. Amplitude:
2. Wavelength (λ):
3. Frequency (f):
4. Period (T):
Read pp. 490-494 in your textbook.
5. If you know the frequency (f) of a wave, what is the formula for calculating the period (T)?
(it is shown on the last page of this handout).
6. What is the period of a pendulum that takes one second to make a complete back-and-forth vibration?
7. What is the period of a pendulum that makes 60 complete back-and-forth vibrations in 15 seconds?
8. Which pendulum has the shorter length of string, one with a period of a whole second or one with a period of
a half second?
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9. If an object vibrates at 500 cycles per second, what is its frequency in kiloherz (kHz)? (use units in your
answer)
10. Does the period of a pendulum depend on the mass of the weight that is swinging?
11. How far, in terms of wavelength, does a wave travel in one period?
Weekend homework12. How many vibrations per second are associated with a 101-MHz radio wave?
A. less than 101,000,000
B. 101,000,000
C. more than 101,000,000
13. An object that completes 20 vibrations in 10 seconds has a
frequency of
A.
B.
C.
D.
0.5 hertz.
1 hertz.
2 hertz.
200 hertz.
Read pp. 495-496 in your textbook.
14. How do you calculate the speed of a wave (in English)?
15. What is the formula for calculating the speed of a wave?
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Measuring waves. Fill in all blanks (1/2 p. each)
One full wave (cycle)
Wave train – two or more waves
Amplitude – measures the energy of a transverse wave
a) measured from the equilibrium position to the top of a crest or the bottom
of a trough (see vertical arrow)
Wavelength – length of a single wave cycle (horizontal arrow double sided arrow)
Frequency-# of waves that pass a point in a given amount of time
Speed = wavelength x frequency
The time from the beginning to the end of the wave train in each situation is 1 second.
Wave 1
a) How many waves are there in this wave train? _____
b) Wavelength ______ cm
c) Amplitude _______ cm
d) frequency ________ Hz
e) speed _______ cm/s
d) frequency ______ Hz
e.) speed _____ cm/s
d) frequency ______ Hz
e.) speed _____ cm/s
Wave 2
a) How many waves are there in this wave train? _____
b) Wavelength ______ cm
c) Amplitude _______ cm
Wave 3
a) How many waves are there in this wave train? _____
b) Wavelength ______ cm
c) Amplitude _______ cm
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Wave 4
If this entire wave train is 30 meters long what is the wavelength of this wave? _______
Monday's homework
16. Calculate the speed of waves in a puddle that are 0.15 m apart and made by tapping the water surface twice
each second.
17. Calculate the speed of waves in water that are 0.4 m apart and have a frquency of 2 Hz.
Read pp. 497-498 in your textbook.
18. What are some examples of transverse waves?
19. What is an example of a longitudinal wave?
Questions based on Bill Nye- Waves (23:02 long), watch 12:24-17:00
20. What are seismic waves?
21. What is it called when a plane reaches the speed of sound and the air molecules in front of the plane's nose
can't move out of the way quick enough?
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22. (3 pts.) In the pipe organ, the length of the pipe determines the pitch Fill in the table below:
length of pipe wavelength pitch
(short, long)
of sound
(low, high)
wave
(short, long)
Read section 25.9 on pp. 501-503 in your textbook
23. A Doppler effect occurs when a source of sound moves
A.
B.
C.
D.
toward you.
at right angles to you.
both of these
none of these
24. The Doppler effect occurs, when the source of sound moves,
A.
B.
C.
D.
for all waves, whether or not the source of the wave moves.
for all waves, when the source of the wave moves.
only for waves in a medium, like sound, but not for light.
only for waves in a medium and only when the source of the wave moves.
Tuesday's homework
Questions based on YouTube "Slinky Demo" by cstephenmurray (4:59 long), just watch 0:00- 2:15.
25. Why can the letter "T" help you remember how a transverse wave differs from a longitudinal one?
26. Does changing the amplitude of the wave affect the speed at which it propagates?
27. Does increasing the tightness of the spring (Slinky) affect the speed at which waves propagate?
28. What happens when a transverse and a longitudinal wave meet in the center of the Slinky?
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Questions based on Bill Nye- Sound (23:03 long), watch 0:58-3:39
29. How much faster does sound travel through metal than though air?
Read pp. 515-519 in your textbook
30. How does pitch relate to frequency?
31. (2 pts.) Light can travel through a vacuum, as we know. Can sound also travel through a vacuum? Explain
why or why not?
32. (2 pts.) When watching at a baseball game, we often hear the bat hitting the ball after we actually see the
hit. Why?
33. (Extra credit- 3 pts.) At a concert, the oboe is playing a long steady note as you walk away from the stage
at an accelerating velocity toward the restroom. The pitch of the sound that you hear is
A.
B.
C.
D.
steady, but higher than normal.
steady, but lower than normal.
continually decreasing.
continually increasing.
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WAVES: Main Concepts
Central Concept: Waves carry energy from place to place without the transfer of matter.
o A vibration is the source of all waves.
o Features of a Wave
Amplitude: the distance from the midpoint to the highest point of the wave crest or the lowest point of
the wave trough.
Wavelength (λ): the distance form crest to crest, trough to trough, or one point on the wave to where it
repeats its pattern.
Frequency (f): the number of waves that pass per second.
Period (T): the time it takes for one wave to pass.
Units for amplitude (meters), wavelength (meters), frequency (hertz or cycles/sec), wave speed (m/s),
and period (seconds.)
Period and frequency are inverses of each other.
T=
1
f
Use the wave speed equation to solve word problems involving wave speed, wavelength, and frequency.
v = fl
o Distinguish between the two types of mechanical waves, transverse and longitudinal.
Transverse waves: the particles move perpendicular to the motion of the energy.
 Waves on a string are an example of transverse waves.
Longitudinal waves: the particles move parallel to the motion of the energy.
 Sound waves are an example of longitudinal waves.
o Distinguish between the electromagnetic and mechanical waves.
Electromagnetic waves can travel through a vacuum (empty space)
Mechanical waves require a medium.
o The medium and its characteristics determine the wave speed.
Mechanical waves (e.g., sound) generally move faster through a solid than through a
liquid and faster through a liquid than through a gas.
All electromagnetic waves travel at the speed of light – very fast, 3 x 108 m/s
o Simple harmonic motion describes the oscillation of particles in a wave. The movement is similar to a
spring or a pendulum.
o The Doppler Effect describes the apparent change in frequency of a wave due to the motion of a source or a
receiver.
Sound: change in pitch.
Light: change in color.
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