Get the Gizmo ready:
Activity B:
Click Reset. Check that Transverse is selected.
Wave dynamics Set Amplitude to 20.0 cm, Frequency to 0.75 Hz,
Tension to 3.0 N, and Density to 1.0 kg/m.
Question: What factors affect the wavelength, speed, and power of waves?
1. Record: The speed of a wave is the distance a wave pulse travels per second. The wave
speed is displayed below the spring. Click Play. What is the wave speed? 173.2cm s
2. Experiment: The wavelength and speed of a wave can be influenced by many factors.
Adjust the amplitude, frequency, tension, and density as described in the table below. Then
report whether this causes the wavelength and wave speed to increase or decrease. Return
each variable to its original value after each experiment.
Adjustment Effect on wavelength Effect on wave speed
Increase amplitude
longer taster
Increase frequency
Increase tension
Shorte stove
Increase density
knife 31 8
3. Analyze: Click Reset. Set the Frequency to 0.80 Hz, Tension to 2.0 N, and Density to 2.0
kg/m. Click Play, and then click Pause. Turn on Show rulers.
A. What is the wavelength? 60
B. What is the wave speed?
100
C. How are the wavelength, frequency, and wave speed related?
speed of wave frequency x length
In general, the wave speed (v) can be calculated from the frequency (f) and
wavelength (λ) using the formula v = f • λ.
D. What is the wavelength of a wave with f = 0.9 Hz and v = 154.9 cm/s?
172 I
To check, set Frequency to 0.90 Hz, Tension to 2.4 N, and Density to 1.0 kg/m.
E. Change the Density to 1.5 kg/m, and click Play. Based on the wave speed, what do
you expect the wavelength to be?
100 Measure the wavelength to check.
(Activity B continued on next page)
2019
Activity B (continued from previous page)
4. Gather data: Click Reset, and turn off Show rulers. The power of a wave is the amount of
energy it transmits each second. The power of the wave is displayed below the spring when
Play is pressed. Record the wave power for each of the settings below.
Amplitude Frequency Tension Density Power
20.0 cm 0.60 Hz 2.0 N 1.0 kg/m
402 W
40.0 cm 0.60 Hz 2.0 N 1.0 kg/m
1 61W
20.0 cm 0.50 Hz 2.0 N 1.0 kg/m
279
20.0 cm 1.00 Hz 2.0 N 1.0 kg/m
402
20.0 cm 0.60 Hz 2.0 N 1.0 kg/m
20.0 cm 0.60 Hz 4.0 N 1.0 kg/m
402
568
20.0 cm
20.0 cm
0.60 Hz
0.60 Hz
2.0 N
2.0 N
0.5 kg/m
1.0 kg/m
1284
402
Which factors increased the power of the wave? low frequency
5. Compare: Click Reset. Select Longitudinal waves. Set Amplitude to 20.0 cm, Frequency
to 0.60 Hz, Tension to 2.0 N, and Density to 1.0 kg/m. Click Play.
A. What is the power of this longitudinal wave? 402
B. Compare this power to the power of a transverse wave with the same settings. Does
changing the type of wave affect its power? no
6. Apply: Sound waves are longitudinal waves that can travel through air. Would you expect
sound waves to travel faster through a low-density gas (such as helium) or a higher-density
gas such as carbon dioxide? Justify your answer based on what you have learned.
higher density
7. Apply: As ocean waves approach the shore, friction with the ocean bottom causes them to
slow down. If the frequency is the same, how will this affect the wavelength of the waves?
friction with the sand it will
shorten the more
lengths
2019
Get the Gizmo ready:
Activity C:
Click Reset. Select Combined waves.
Combined waves Set Amplitude to 10.0 cm, Frequency to 0.75 Hz,
Tension to 2.0 N, and Density to 1.0 kg/m.
Question: What does wave motion look like when transverse and longitudinal waves are
combined?
1. Observe: Click Play. Observe the motions of the hand and of the green dot in the middle.
A. What is the motion of the hand?
circular
B. Deselect the Lights on checkbox. What is the motion of the green dot?
circular
In a combined wave, the motion of the medium is circular. So, each point of the
spring moves in a circle as the wave is transmitted from left to right.
C. Click Pause. Compare the crests (high points) to the troughs (low points). What do
you notice? same height
Combined waves, such as ocean waves, do not look exactly like transverse waves.
In the Gizmo, the troughs are pointy and the crests are rounded. In the ocean, the
crests are relatively pointy while the troughs are rounded.
2. Measure: Click Reset. Select Lights on and Show rulers. Set the Frequency to 1.0 Hz.
Check that the Tension is 2.0 N, the Density is 1.0 kg/m, and the Amplitude is 10.0 cm.
A. Measure the horizontal distance between two crests. What is this distance? 25cm
B. What is the distance between two troughs? 160 on
C. How do the wavelength, wave speed, and wave power of the combined wave
compare to a transverse wave with the same settings? Explain.
shorter but faster plus circular motion
and stronger rare
D. Why do you think the combined wave is more powerful than either the transverse or
longitudinal wave with the same amplitude, frequency, tension, and density?
2019
