Question

1. Open the Wave on a String PhET simulation.
2. Set the following parameters:

Simulation	PAUSED
Damping	None
Tension	High
Rope’s End	No End
Source	Oscillate
Ruler	Enabled
Amplitude	0.5 cm

3. Set the frequency of oscillation to 1.5 Hz. Run the simulation by clicking on the Play/Pause button. Measure the wavelength of the wave, using the ruler and the Play/Pause button.

4. Repeat step 3 but increase the frequency to 3 Hz. Determine the wavelength of the wave. Summarize your data in Data Table 1. Calculate the wave speed for each frequency.

Data Table 1

Frequency	Wavelength	Speed
1.5 Hz
3.0 Hz

Questions:

• How did you measure the wavelength of the wave?

• What happened to the wavelength of the wave when the frequency increased from 1.5 Hz to 3.0 Hz? What happened to the speed?
• For a rope of uniform density (and tension), what relationship exists between the frequency and the wavelength of the wave?
• Set the following parameters:

Simulation	PAUSED
Damping	None
Rope’s End	No End
Source	Oscillate
Ruler	Enabled
Stopwatch	Enabled
Amplitude	0.5 cm
Frequency	1.5 Hz

2. Set the Tension to “Low” (value = 1 unit). Run the simulation. Using the ruler determine the speed of the wave by measuring the time it takes for the wave to travel by 3 cm. (Hint: Use the “Pause/Play/Step button”)
3. Repeat (2) for “Medium” (value = 9 units) and “High” (value = 25 units) Tension. Summarize your calculations in Data Table 2

Data Table 2

Tension		Distance Travelled, d (cm)	Time Elapsed, t (s)	Speed, v (cm/s)	v2
Low	1 unit	3
Medium	9 units	3
High	25 units	3

4. Using a graph paper of EXCEL, plot the values of the Tension against the values of v². Describe the graph formed.

Questions:

• Describe what you did in determining the speed of the wave.
• What is the effect of increasing the tension in the rope on the speed of the wave?
• Approximately how many times did the speed change when the tension is increased by a factor of 9 (e.g. T_medium/T_low = 9)?
• Approximately how many times did the speed change when the tension is increased by a factor of 9 (e.g. T_medium/T_low = 9)?
• What does the graph of T vs. v² suggest about the relationship between the tension in the rope and the speed of the wave?

1. Open the Wave on a String PhET simulation.

2. Set the following parameters:

Simulation	PAUSED
Damping	None
Tension	High
Rope’s End	No End
Source	Oscillate
Ruler	Enabled
Amplitude	0.5 cm

3. Set the frequency of oscillation to 1.5 Hz. Run the simulation by clicking on the Play/Pause button. Measure the wavelength of the wave, using the ruler and the Play/Pause button.

4. Repeat step 3 but increase the frequency to 3 Hz. Determine the wavelength of the wave. Summarize your data in Data Table 1. Calculate the wave speed for each frequency.

Data Table 1

Frequency	Wavelength	Speed
1.5 Hz
3.0 Hz

Questions:

• How did you measure the wavelength of the wave?

• What happened to the wavelength of the wave when the frequency increased from 1.5 Hz to 3.0 Hz? What happened to the speed?

• For a rope of uniform density (and tension), what relationship exists between the frequency and the wavelength of the wave?

1. Set the following parameters:

Simulation	PAUSED
Damping	None
Rope’s End	No End
Source	Oscillate
Ruler	Enabled
Stopwatch	Enabled
Amplitude	0.5 cm
Frequency	1.5 Hz

2. Set the Tension to “Low” (value = 1 unit). Run the simulation. Using the ruler determine the speed of the wave by measuring the time it takes for the wave to travel by 3 cm. (Hint: Use the “Pause/Play/Step button”)

3. Repeat (2) for “Medium” (value = 9 units) and “High” (value = 25 units) Tension. Summarize your calculations in Data Table 2

Data Table 2

Tension		Distance Travelled, d (cm)	Time Elapsed, t (s)	Speed, v (cm/s)	v2
Low	1 unit	3
Medium	9 units	3
High	25 units	3

4. Using a graph paper of EXCEL, plot the values of the Tension against the values of v². Describe the graph formed.

Questions:

• Describe what you did in determining the speed of the wave.

• What is the effect of increasing the tension in the rope on the speed of the wave?

• Approximately how many times did the speed change when the tension is increased by a factor of 9 (e.g. T_medium/T_low = 9)?

• Approximately how many times did the speed change when the tension is increased by a factor of 9 (e.g. T_medium/T_low = 9)?

• What does the graph of T vs. v² suggest about the relationship between the tension in the rope and the speed of the wave?

Answer 1