Gizmo: Waves

Instructions

Observe and measure transverse, longitudinal, and combined waves on a model of spring moved by a hand. Adjust the amplitude and frequency of the hand, and the tension and density of the spring. The speed and power of the waves is reported, and the wavelength and amplitude can be measured.

https://gizmos.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=1053

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A buoy is anchored to the ocean floor.
A large wave approaches the buoy. How will the buoy move as the wave goes by?

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The two images show side views of ocean waves.
How are the two sets of waves different?

Ocean swells are an example of waves. In the Waves Gizmo, you will observe wave motion on a model of a spring. The hand can move the spring up and down or back and forth. 
 

To begin, check that the Type of wave is Transverse,
Amplitude is 20.0 cm,
Frequency is 0.75 Hz,
Tension is 3.0 N, and
Density is 1.0 kg/m.
(Note: In this Gizmo, “density” refers to the linear mass density or mass per unit length. It is measured in units of kilograms per meter.)

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Click Pause
What do you notice about the crests (high points) _______ and troughs (low points)_______ of the wave.

Click Reset. 
Choose the Longitudinal wave
increase the Amplitude to 20.0 cm.

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Click Play.
How would you describe the motion of a longitudinal wave?

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Observe: Click Play. Observe the motions of the hand and of the green dot in the middle.

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What is the motion of the hand?

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In a transverse wave, the motion of the medium (what the wave moves through—in this case, the spring) is perpendicular to the direction of the wave. So, each point of the spring moves up and down as the wave travels from left to right.

Measure: With the lights on, click Pause. Turn on Show rulers.

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Use the horizontal ruler to measure the horizontal distance between two crests. What is this distance?
This is the wavelength of the wave.

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What is the distance between the two troughs?
The wavelength can be found by measuring the distance between two successive crests, two successive troughs, or any two equivalent points on the wave.

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Measure: Click Reset. The amplitude of a transverse wave is the maximum distance a point on the wave is displaced, or moved, from its resting position. 
Turn off the lights.
Click Play, and then click Pause. 
Use the vertical ruler to measure the height of the green trace, showing how far the green dot moved up and down.

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What is the height of the green trace?

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The wave’s amplitude is equal to half of this height. What is the amplitude?

Observe: 
Click Reset. 
Select Lights on 
and turn off Show rulers. 

Select Longitudinal waves.
 
Check that the 
Amplitude is 10.0 cm, 
the Frequency is 1.00 Hz, 
and the Tension is 2.0 N. 
Set the Density to 1.0 kg/m, 
and click Play.

In a longitudinal wave, the motion of the medium is parallel to the direction of the wave. So, each point of the spring moves back and forth as the wave is transmitted from left to right.

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Measure: 
With the lights on, click Pause. 
Turn on Show rulers.

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The wavelength of a longitudinal wave is equal to the distance between two successive compressions (or rarefactions). What is this distance?

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Measure: 
Click Reset. 
The amplitude of a longitudinal wave is equal to the distance a point on the wave is displaced from its resting position. 
Turn off the lights. 
Click Play, and then click Pause. 
Use the horizontal ruler to measure the width of the green trace.

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What is the width of the green trace?

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The wave’s amplitude is equal to half of this height. What is the amplitude?

Calculate: 
Click Reset. 
Select Transverse waves.
Select Lights on and Show grid 
and turn off Show rulers. 
Set the Frequency to 0.50 Hz. 

A single cycle is the time it takes the hand to 
move up, move down,
and then back up to the starting position. (middle)
Click Play, and then click Pause after exactly one cycle. (This may take a few tries.)

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How long does one cycle take?
This is the period (T) of the wave.

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Amplitude: 20.0 cm
Frequency: 0.75 Hz
Tension: 3.0 N
Density: 1.0 kg/m

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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?

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.

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Increase Amplitude

Effect on wavelength __________

Effect on wave speed __________

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Increase Frequency

Effect on wavelength __________

Effect on wave speed __________

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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.

In general, the wave speed (v) can be calculated from the frequency (f) and wavelength (λ)
using the formula v  = f • λ.

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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 to the right.

Measurements in red are what is being changed

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Which factors increased the power of the wave when they were increased?

Amplitude  Frequency Tension  Density

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.

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What is the power of this longitudinal wave?

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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.

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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?

Observe: Click Play. Observe the motions of the hand and of the green dot in the middle.

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.

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.

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Click Pause. Compare the crests (high points) to the troughs (low points). What do you notice?

Measure: Click Reset. S
elect 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.

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Measure the horizontal distance between two crests. What is this distance?

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What is the distance between two troughs?

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What type of wave is shown below?

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What is the amplitude and wavelength of the wave shown below?

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What is the best estimate of the frequency of the wave shown below?

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What is the best estimate of the frequency of the wave shown below?

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Gizmo: Waves

A buoy is anchored to the ocean floor. A large wave approaches the buoy. How will the buoy move as the wave goes by?

The two images show side views of ocean waves.How are the two sets of waves different?

Click Play. How would you describe the motion of a longitudinal wave?

What is the motion of the hand?

Use the horizontal ruler to measure the horizontal distance between two crests. What is this distance?This is the wavelength of the wave.

What is the distance between the two troughs?The wavelength can be found by measuring the distance between two successive crests, two successive troughs, or any two equivalent points on the wave.

What is the height of the green trace?

The wave’s amplitude is equal to half of this height. What is the amplitude?

The wavelength of a longitudinal wave is equal to the distance between two successive compressions (or rarefactions). What is this distance?

What is the width of the green trace?

The wave’s amplitude is equal to half of this height. What is the amplitude?

How long does one cycle take?This is the period (T) of the wave.

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?

Which factors increased the power of the wave when they were increased?

What is the power of this longitudinal wave?

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.

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?

Click Pause. Compare the crests (high points) to the troughs (low points). What do you notice?

Measure the horizontal distance between two crests. What is this distance?

What is the distance between two troughs?

What type of wave is shown below?

What is the amplitude and wavelength of the wave shown below?

What is the best estimate of the frequency of the wave shown below?

What is the best estimate of the frequency of the wave shown below?

How could you increase the power of a wave in a spring?

A buoy is anchored to the ocean floor. A large wave approaches the buoy. How will the buoy move as the wave goes by?

The two images show side views of ocean waves.How are the two sets of waves different?

Click PlayHow would you describe the motion of a transverse wave?

Click Play. How would you describe the motion of a longitudinal wave?

What is the motion of the hand?

Turn off the Lights on the checkbox and observe the green dot. What is the motion of the green dot?

Follow the motion of a single crest of the wave. How does the crest move?

Use the horizontal ruler to measure the horizontal distance between two crests. What is this distance?This is the wavelength of the wave.

What is the distance between the two troughs?The wavelength can be found by measuring the distance between two successive crests, two successive troughs, or any two equivalent points on the wave.

Click Reset. Set the Density to 1.0 kg/m.Click Play, and then Pause. What is the wavelength of this wave?

What is the height of the green trace?

The wave’s amplitude is equal to half of this height. What is the amplitude?

What is the motion of the hand

Turn the lights off. What is the motion of the green dot.

Follow the motion of a single compression of the wave. How does the compression move?

The wavelength of a longitudinal wave is equal to the distance between two successive compressions (or rarefactions). What is this distance?

How does this compare to the wavelength of the comparable transverse wave? (See your answer to question 12)

What is the width of the green trace?

The wave’s amplitude is equal to half of this height. What is the amplitude?

How long does one cycle take?This is the period (T) of the wave.

Frequency (f) is equal to 1 divided by the period: f = 1 / TFrequency is measured in hertz (Hz), where 1 Hz = 1 cycle/sec.What is the frequency of this wave?*Take 1 / your answer from 22

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?

What is the wavelength?

What is the wave speed?

How are the wavelength, frequency, and wave speed related?

What is the wavelength of a wave with f = 0.9 Hz and v = 154.9 cm/s? v = f • λ.154.9 = 0.9 • λ.To check, set Frequency to 0.90 HzTension to 2.4 N, and Density to 1.0 kg/m.

Which factors increased the power of the wave when they were increased?

What is the power of this longitudinal wave?

Compare this power to the power of a transverse wave with the same settings. Does changing the type of wave affect its power?

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.

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?

What is the motion of the hand?

Deselect the Lights On checkbox. What is the motion of the green dot?

Click Pause. Compare the crests (high points) to the troughs (low points). What do you notice?

Measure the horizontal distance between two crests. What is this distance?

What is the distance between two troughs?

How do the wavelength, wave speed, and wave power of the combined wave compare to a transverse wave with the same settings? Explain.

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?

What type of wave is shown below?

What is the amplitude and wavelength of the wave shown below?

What is the best estimate of the frequency of the wave shown below?

What is the best estimate of the frequency of the wave shown below?

How could you increase the power of a wave in a spring?

Click PlayHow would you describe the motion of a transverse wave?

Turn off the Lights on the checkbox and observe the green dot. What is the motion of the green dot?

Follow the motion of a single crest of the wave. How does the crest move?

Click Reset. Set the Density to 1.0 kg/m.Click Play, and then Pause. What is the wavelength of this wave?

What is the motion of the hand

Turn the lights off. What is the motion of the green dot.

Follow the motion of a single compression of the wave. How does the compression move?

How does this compare to the wavelength of the comparable transverse wave? (See your answer to question 12)

Frequency (f) is equal to 1 divided by the period: f = 1 / TFrequency is measured in hertz (Hz), where 1 Hz = 1 cycle/sec.What is the frequency of this wave?*Take 1 / your answer from 22

What is the wavelength?

A buoy is anchored to the ocean floor.
A large wave approaches the buoy. How will the buoy move as the wave goes by?

The two images show side views of ocean waves.
How are the two sets of waves different?

Click Play.
How would you describe the motion of a longitudinal wave?

Use the horizontal ruler to measure the horizontal distance between two crests. What is this distance?
This is the wavelength of the wave.

What is the distance between the two troughs?
The wavelength can be found by measuring the distance between two successive crests, two successive troughs, or any two equivalent points on the wave.

How long does one cycle take?
This is the period (T) of the wave.

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.

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?

A buoy is anchored to the ocean floor.
A large wave approaches the buoy. How will the buoy move as the wave goes by?

The two images show side views of ocean waves.
How are the two sets of waves different?

Click Play
How would you describe the motion of a transverse wave?

Click Play.
How would you describe the motion of a longitudinal wave?

Use the horizontal ruler to measure the horizontal distance between two crests. What is this distance?
This is the wavelength of the wave.

What is the distance between the two troughs?
The wavelength can be found by measuring the distance between two successive crests, two successive troughs, or any two equivalent points on the wave.

Click Reset.
Set the Density to 1.0 kg/m.
Click Play, and then Pause.

What is the wavelength of this wave?

How long does one cycle take?
This is the period (T) of the wave.

Frequency (f) is equal to
1 divided by the period:
f = 1 / T

Frequency is measured in hertz (Hz),
where 1 Hz = 1 cycle/sec.

What is the frequency of this wave?
*Take 1 / your answer from 22

What is the wavelength of a wave with
f = 0.9 Hz and v = 154.9 cm/s?
v = f • λ.
154.9 = 0.9 • λ.

To check, set
Frequency to 0.90 Hz
Tension to 2.4 N, and
Density to 1.0 kg/m.

Compare this power to the power of a transverse wave with the same settings.
Does changing the type of wave affect its power?

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.

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?

Click Play
How would you describe the motion of a transverse wave?

Click Reset.
Set the Density to 1.0 kg/m.
Click Play, and then Pause.

What is the wavelength of this wave?

Frequency (f) is equal to
1 divided by the period:
f = 1 / T

Frequency is measured in hertz (Hz),
where 1 Hz = 1 cycle/sec.

What is the frequency of this wave?
*Take 1 / your answer from 22

What is the wavelength of a wave with
f = 0.9 Hz and v = 154.9 cm/s?
v = f • λ.
154.9 = 0.9 • λ.

To check, set
Frequency to 0.90 Hz
Tension to 2.4 N, and
Density to 1.0 kg/m.

Compare this power to the power of a transverse wave with the same settings.
Does changing the type of wave affect its power?