Lab 9: Standing Waves (Waves on a String)
Name Date
Assignment Submission Directions: Download this assignment sheet and complete by answering all questions. You will
need to access the simulations website in order to complete the labs. When completed, save your work and upload the
document to the Assignment Upload for graded submission. 50 points.
Items in red font require submission into a pre populated text box shown as Click here to enter text. (Note: you do not
need to fill this one in, for directions purposes only.)
Part A: Using Transformations to Graph Linear Functions
Simulation Website: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html
Learning Goals
● Discuss wave properties using common vocabulary.
● Predict the behavior of waves through varying medium and at reflective endpoints.
● Observe relationships between frequency, wavelength, and speeds of waves.
● Observe how these change with changing tension in the rope.
Activity
Part 1: Speed of Wave and Tension
● Set to ‘Pulse’
● Set to ‘Fixed End’
● Damping = None
● Tension = Low
● Check to display ‘Ruler’ and ‘Timer’
1. Use the ruler to measure the length of the piece of string. Record
2. Click the button on the pulse generator to send a pulse through the string
3. Use the timer to measure how long it takes for the pulse to travel back and forth 5 times.
4. Repeat on ‘Moderate’ and ‘High’ Tension
String length = 0.075cm
A B C D E
Speed ∆𝑥
Tension Time for pulse to travel 5 Average Time for one Length of one round of wave 𝑣 =
𝑡
round trips round trip (Column A/5) trip Column D/C
Low 59 11.8 0.15 0.013
Medium 19 3.8 0.15 0.039
High 12 2.4 0.15 0.06
5. Create a bar graph comparing the wave speeds vs tension for your three trials and insert it below. Answer
the question for the graph.
, Lab 9: Standing Waves (Waves on a String)
6. Explain your graph in terms of wave propagation along the string based on the tension settings. How do the waves
behave?
The graph shows how tension in a string affects wave speed. When the tension is low, waves move slower (0.013
units) because the string isn’t very elastic. With medium tension, the wave speed increases (0.039 units), showing a
good balance between elasticity and the string’s weight. At high tension, the waves travel the fastest (0.06 units)
because the string becomes more elastic and less affected by inertia. Overall, the graph proves that as tension
increases, waves move faster along the string.
Part 2: String Wave Interference
● Restart Pulse Mode.
● Set the Amplitude to the largest possible value.
● Pulse Width to the largest possible value.
● Damping set to None.
● Tension set to Low.
7. Send a pulse down the string. When it reaches the other end, send another pulse down the string.
Switch to Slow Motion and try to hit pause at the exact moment when the pulses overlap. Notice the pattern made at
the moment of complete overlap. Was this interference constructive or destructive?
Constructive: When the pulses overlap, the peaks line up perfectly, combining to form a larger wave. This shows
constructive interference.
Name Date
Assignment Submission Directions: Download this assignment sheet and complete by answering all questions. You will
need to access the simulations website in order to complete the labs. When completed, save your work and upload the
document to the Assignment Upload for graded submission. 50 points.
Items in red font require submission into a pre populated text box shown as Click here to enter text. (Note: you do not
need to fill this one in, for directions purposes only.)
Part A: Using Transformations to Graph Linear Functions
Simulation Website: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html
Learning Goals
● Discuss wave properties using common vocabulary.
● Predict the behavior of waves through varying medium and at reflective endpoints.
● Observe relationships between frequency, wavelength, and speeds of waves.
● Observe how these change with changing tension in the rope.
Activity
Part 1: Speed of Wave and Tension
● Set to ‘Pulse’
● Set to ‘Fixed End’
● Damping = None
● Tension = Low
● Check to display ‘Ruler’ and ‘Timer’
1. Use the ruler to measure the length of the piece of string. Record
2. Click the button on the pulse generator to send a pulse through the string
3. Use the timer to measure how long it takes for the pulse to travel back and forth 5 times.
4. Repeat on ‘Moderate’ and ‘High’ Tension
String length = 0.075cm
A B C D E
Speed ∆𝑥
Tension Time for pulse to travel 5 Average Time for one Length of one round of wave 𝑣 =
𝑡
round trips round trip (Column A/5) trip Column D/C
Low 59 11.8 0.15 0.013
Medium 19 3.8 0.15 0.039
High 12 2.4 0.15 0.06
5. Create a bar graph comparing the wave speeds vs tension for your three trials and insert it below. Answer
the question for the graph.
, Lab 9: Standing Waves (Waves on a String)
6. Explain your graph in terms of wave propagation along the string based on the tension settings. How do the waves
behave?
The graph shows how tension in a string affects wave speed. When the tension is low, waves move slower (0.013
units) because the string isn’t very elastic. With medium tension, the wave speed increases (0.039 units), showing a
good balance between elasticity and the string’s weight. At high tension, the waves travel the fastest (0.06 units)
because the string becomes more elastic and less affected by inertia. Overall, the graph proves that as tension
increases, waves move faster along the string.
Part 2: String Wave Interference
● Restart Pulse Mode.
● Set the Amplitude to the largest possible value.
● Pulse Width to the largest possible value.
● Damping set to None.
● Tension set to Low.
7. Send a pulse down the string. When it reaches the other end, send another pulse down the string.
Switch to Slow Motion and try to hit pause at the exact moment when the pulses overlap. Notice the pattern made at
the moment of complete overlap. Was this interference constructive or destructive?
Constructive: When the pulses overlap, the peaks line up perfectly, combining to form a larger wave. This shows
constructive interference.
