# Sound Waves

Need a Review? Revisit Last Week's "Waves"

# (Monday, 2/26/2018)

Open up Laptop to PENDULUM LAB on Phet Simulator: https://phet.colorado.edu/sims/html/pendulum-lab/latest/pendulum-lab_en.html

(If you are having difficulty accessing the Simulator, go to phet.colorado.edu, and search Pendulum Lab HTML5)

While going through the Pendulum Simulator (15 minutes), take note of changes when you:

1. Change the Mass of the Pendulum after it is already moving.
2. Change the Length of the Pendulum after it is already moving.
3. Change the Angle of the Pendulum after it is already moving.

As a Class, review the Pendulum and Period Powerpoint. Access the PDF for later studying here [COMING SOON- After School on Monday].

## Waves on a String

Open the PHET Simulator using the URL https://phet.colorado.edu/en/simulation/wave-on-a-string, if this URL does not work, go to phet.colorado.edu and search for “Waves on a String: HTML 5” – Press Play

GET TO KNOW THE SIMULATOR: Complete the following, you DO NOT have to answer the QUESTIONS for Part 1,

## Part 1

AGAIN, YOU DO NOT NEED TO ANSWER THESE QUESTIONS (2-6), THEY ARE MEANT TO HELP YOU GET TO KNOW THE SIMULATOR.

1. Begin with the Left Hand Selection to “Manual” and Right Hand Selection to “Fixed End.” Complete the following:

A. With your mouse pad, click on the wrench (left side of the screen), drag the wrench up and down. What movements do you need to make to create a constant wave?

2. Change the Left Hand Selection to “Oscillate” and Right Hand Selection to “Fixed End.” The Amplitude should be set to 0.75 cm, and the Frequency to 1.50 Hz.

A. Slowly move the Amplitude from 0.75 cm to 0.85 cm. What happens to the wave as it is changing?
B. Change the “Damping” to Medium. Damping adds mass to the string.  What do you notice about the amplitude of the wave as it approaches the fixed end? You can change to speed to “Slow Motion” if you are having trouble.
C. Why do you think adding mass causes this?

3. Change the Right Hand Selection to “Loose End” and change the Damping to “None.”
A. What happens to the wave as time goes on? Why do you think this?
B. Press “Restart” and change the frequency to 3.00Hz, What is happening to the Period of the wave?
C. Begin changing the Frequency to 2.00 Hz while the wave is still moving. What happens as he waves collide? Spend some time watching this change.
D. How long does it take for a consistent period and amplitude. (You can turn on the Timer in the lower right hand corner for assistance)

4. Without changing Amplitude, Frequency, or “Oscillation,” Change the Right Hand Selection to “No End”
A. What immediately happens to the wave?
B. How does this type of end compare to the “Loose End”?  You can click back and forth between “Loose End” and “No End” for help.

5. Press the “Restart” button in the lower right hand corner, change the Left Hand Selection to “Pulse,” The right hand selection to be to “Fixed End.” Amplitude should be at 0.75 cm and Pulse width should be at 0.5s. Set the Speed to Slow Motion
A. Press the Green Button to send a single Pulse. What happens to the wave as it moves toward the fixed end?
B. Change the Right hand Selection to “Loose End,” send a single pulse down. What do you notice happens after the pulse hits the “Loose End?”
C. Now send multiple pulses down the string. What happens? (This will help with settings to “Slow Motion”

When you have a good idea of how the SIMULATOR WORKS: Complete part 2 on a separate sheet of paper and turn into the basket when finished!

## Part 2

WAVES ON A STRING ASSIGNMENT

Complete questions 1-12 on your own using a separate sheet of paper.

## Venn Diagram

When finished, in your notes you should complete a Venn Diagram, similar to the one below, comparing and conrasting TRANSVERSE and LONGITUDINAL waves. You can use the internet for assistance. Venn Diagrams will be check on Thursday/Friday for Completion.

## Notes

Constructive vs. Destructive Interference

Write your OWN definition in your notes of what Constructive and Destructive interference is.

DOPPLER EFFECT VIDEO

# Waves Assignment 8

Answer the following questions on a separate sheet of paper and turn into the basket.

1. Compare the direction in which people move in a people wave and the way a wave moves.
2. You sent a pulse down a Slinky.
A) Which way did the pulse move?
B) Did the shape of the pulse change as it moved?
C)  What happened to the pulse when it reached the end of the Slinky?
3. Draw a wave and label all parts of a wave. What kind of wave did you draw (transverse or longitudinal?)
4. What kind of wave is this? (Slinky) Describe the movement of the wave and the way the medium moves.
5. Two pulses travel down a Slinky, each form opposite ends and meet in the middle. What do the pulses look like when they meet? Make a sketch. What do the pulses look like after they pass each other? Make a sketch.
6. In your own works, compare frequency and period.
7. What determines the speed of a wave?
8. Find the velocity of a 2-m long wave with a frequency of 3.5 Hz
9. Find the period of a wave with the frequency of 3 Hz