Name:



Name: ___________________

Waves Virtual Lab

Directions:

-Go to:

- Type “wave on a string” in the search bar.

- Click on the wave on a string simulation and click “run now”

Wave on a string simulation

1. Set the damping to zero. Click fixed end and set it to pulse. Hit the green pulse icon and draw what you see when the wave hits the fixed end and switches direction.

2. Leave the same settings as #1 using a loose end. Hit the green pulse icon and draw what you see when the wave hits the loose end and switches direction.

3. What is the difference between the reflected wave off of a fixed end and a loose end?

4. Use the same settings as #1. Hit the pulse button 2 times and then immediately hit the pause button. Draw what is now paused on your screen.

5. Use the ruler (this box will need to be checked) to measure the wavelength of the waves you have created. What is the wavelength of your waves?

6. Using the wavelength from question # 5, what would be the speed of your waves if the frequency of the waves was 300 Hertz? (formula: wave speed = wavelength x frequency) SHOW YOUR WORK!

7. Put all of your settings back to how they were for #1. Set the tension to “low”. Click the pulse button. What has happened to the speed of your wave? Why has this happened?

Directions:

- Exit out of the “wave on a string” simulation

- Go back to the main Phet website and type in “sound”

- Click on the sound simulation and click “run now”

Sound Simulation

1. Set the audio control to listener. Make sure the audio is enabled (let me know if you cannot hear the sound coming from your speaker).

2. Move the listener away from the speaker. What happens to the sound that you hear? Why?

3. Move the listener towards the speaker. What happens to the sound you hear? Why?

4. Raise the amplitude of the speaker to its highest setting and then move it to the lowest setting. What happens to the sound that you hear when the amplitude is raised? What happens when the amplitude is lowered? Based on your answers, what is the relationship between amplitude and loudness?

5. Set all settings back to how they were for question #1 (make sure the listener is back to his or her original position). Raise the frequency to 1,000 Hz and then lower it to 200 Hz. What happens to the sound? Based on your observations, how are pitch and frequency related?

6. Click on the measure tab. Set the frequency to 172 Hz and let it play for 5 seconds. After 5 seconds hit the pause button. Measure the wavelength of the sound wave (compression to compression). What is the wavelength of your sound wave?

7. Using the frequency and wavelength you just found. Find the speed of a sound wave. SHOW WORK!

(wave speed = frequency x wavelength)

8. What would happen to the speed of your sound wave if the medium was the ocean? Why?

9. Click on the “Listen with varying air pressure” tab. Click on the listener tab. Make sure the audio is enabled. When you begin to hear the sound, click on the “remove air from box” button. What happens to the sound you are hearing as the air is removed? Why?

Bonus:

A popular science fiction movie depicts an epic starfighter battle in outer space. The movie ends with the good guys blowing up the bad guy’s spaceship. In the movie the explosion of the bad guy’s spaceship can be seen and the explosion is followed by an extremely loud “bang”. Though the movie won an Academy Award, it is not completely accurate. What is wrong (scientifically) with this movie?

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