Hannah Lexer\'s 1 - This was a phet I completed in class. PDF

Preview

Summary

This was a phet I completed in class....

Description

1.3 Sound Wave PhET Procedure: 1. Go to http://phet.colorado.edu/en/simulation/sound 2. Click on “Download” (see below)

3. You will get this message:

Click “OK” 4. Open your System Preferences. Go to the “Security and Privacy” pane. 5. Click on “Open anyway”

The program should now open automatically!!

Listen to a Single Source: 1. Go to the tab “Listen to a Single Source.” Observe the sound waves coming from the speaker. a) What do the dark and light bands represent? (Remember, sound waves are longitudinal waves.) Answer: The dark bands represent the waves that are closer to the source, and the light bands are when they are farther away from the source. b) Why do the waves get lighter with distance from the speaker? Answer: The waves get lighter because with distance the sound decreases the sound and you wouldn’t be able to hear it as much as if you were right by the source. c) How does changing the frequency and amplitude affect the depiction of the sound waves in the simulation? Answer:When increased the amplitude it makes the waves become farther apart from each other. But, when you increase the frequency the waves get closer together. d) How do you think changing the frequency and amplitude affect the sound heard by the listener? (You can enable audio for this if need be). Answer: When increasing the amplitude it makes the sound go louder, and when you increase the frequency it makes more of an ear piercing sound(the pitch). But, if the frequency or amplitude is turned off all of the way the other one won’t be able to work. STOP. Check with your teacher before you move on. 20%

Teacher initials _____ek___ Progress =

Measure: 2. Go to the tab “Measure.” Press “start” and move the ruler to the center of the speaker. a) Look at the stopwatch. Notice that it doesn’t work like a typical stopwatch instead it is much slower! Why is it programmed this way? What would you be able to see if the stopwatch ran in “real time?” Answer: It goes depending on how fast the frequency is moving at. So, depending on where the ruler is placed it might go slower or faster. You also wouldn’t be able to see the waves if it was in real time since they would be going so fast. b) Describe how you would find the frequency of a wave if the frequency slider did not have a number display. (Hint: what is the definition of frequency?

How could you figure out the frequency from looking at the picture and using only the tools available?) Answer: You would be able to find the frequency depending on the number of waves it produces per second. Since frequency is the vibrations an object makes in a certain amount of time. So, you would use the timer to time and measure how many waves happen at a time. c) Describe how you would find the period of a wave without using the frequency information. (Hint: what is the definition of period? How could you figure out the period from looking at the picture and using only the tools available?) Answer: You would be able to use the timer to time how long it would take for the wave to get to the beginning to the end. You would line the ruler up to the beginning of the wave to the end and press start when you are ready. STOP. Check with your teacher before you move on.

Teacher initials ________ Progress = 40%

3. Now you will calculate the speed of sound. For this calculation, we will use our basic equation for velocity (v=d/t). In order to do this we will hold time constant, which means that we will choose an amount of time and see how far the wave travels during that set interval. Choose an interval of time and write it in the space below labelled “Measurement Time.” Hit stop and reset, and measure the distance a wave front travels in that chosen amount of time. Record your distance data for three trials in the table below and then calculate the velocity of the wave and write it in the “Calculated v (m/s)” column. Measurement Time: ___________ Distance (m)

Calculated v (m/s)

a) Now we will compare the experimental speed that you calculated using the data taken above with the calculated speed that you will get using the equation v = fλ. Use the ruler to get the wavelength of a wave, your frequency information is given. Show your calculations below using the five step method in the box below. Answer:

STOP. Check with your teacher before you move on.

Teacher initials ________ Progress = 80%

Listening with Varying Air Pressure: 4. Go to the tab “Listening with Varying Air Pressure.” You will need to enable audio to use this tab. a) What happens when you remove the air from the speaker box? Why does this happen? Answer: b) If the box held a light bulb instead of a speaker, would the person still be able to see the light if the air were removed from the box? Why/ why not? Explain your reasoning with an example from real life. Answer: STOP. Check with your teacher before you move on.

Teacher initials ________ Progress = 100%...