DAY 141

Today's video lesson: https://youtu.be/NhsfJO8wJ9c

Essential Questions:What is a wave? How do they act? How do waves differ?

Goals: SWBAT...

1. Discuss waves’ properties using common vocabulary and they will be able to predict the behavior of waves through varying medium and at reflective endpoints

Warm-Up (10min):

1. Introduce yourself to mechanical waves by watching this ---> https://www.flippingphysics.com/waves.html

lecture notes are available here: https://www.flippingphysics.com/uploads/2/1/1/0/21103672/0318_lecture_notes_-_waves_introduction.pdf

2. Which watching, in your notes answer the following:

a. list 5 examples of waves, and classify them as either mechanical or electromagnetic (E&M).

b. Which of these two types requires a medium?

c. What is a medium? For the spring, it's metal. What about for the sound that you hear from the video?

d. Define Transverse Waves. In which direction (up/down or forwards/backwards) would you move your hand to make a transverse wave?

e. Define Longitudinal Waves. In which direction (up/down or forwards/backwards) would you move your hand to make a longitudinal wave?

CLASSWORK

1. #141A: Waves on a String

The goal here is to explore waves a bit. In the video above, you've seen some terms defined, but we still haven't dealt with the vocabulary of amplitude, frequency, etc. Instead of defining those first, I wanted you to play around a bit with sim to get your own idea of what they are, before we get to the official definitions tomorrow.

Obviously, you have no partners, so where I ask you to discuss, you can't (unless you live with your sister, who is also in my class). Still, I left that in there so you'd know where I wanted you to pause and think a bit...

Directions:

1. Read the directions. Then open Waves on a String: (the link is at the bottom of the directions :)

2. With the Oscillate button on, with No End checked, and with Slow Motion on, investigate waves more carefully using the Amplitude slider.

Write answers to the following after your group has talked about each and agreed.

a) Define Amplitude in everyday language.

b) Explain how the wave behaves as the Amplitude changes using the characteristics you described in the warm-up

c) Use a rope/string/ on the floor for some investigations and explain how you could change the Amplitude of a wave.

3. Repeat step number 2, for Frequency, Tension and Damping.

don't skip this step

4. Set Amplitude on high, Frequency to .25Hz, Damping on none, and Tension on low. Also, have on Oscillate, Timer and No End. Use the Pause button to freeze the wave.

a) Place a blank piece of paper on your monitor and trace the wave and the wave generator. Mark the green balls. This is a vertical position- horizontal position graph, label your axes.

b) Quickly press Play, and then Pause again. Use the same piece of paper, put it on the monitor and make sure to get the generator in the same spot. Trace the new wave. Play and Pause a 3rd time. Draw the 3rd wave.

c) Write about the differences and similarities in the characteristics. You may have to do some more tests by pressing Play, then Pause and tracing to test your ideas.

5. Same settings as above in #4. Set Amplitude on high, Frequency to .25Hz, Damping on none, and Tension on low. Also, have on Oscillate, Timer and No End. Use the Pause button to freeze the wave.

a) Measure the vertical location of a green ball with a ruler. B) Record the vertical position and time.

b) Quickly press Play, then Pause repeatedly to make a data table the vertical position of the green ball versus time.

c) Make a graph of vertical position versus time.

d) Write about the differences and similarities between vertical position- horizontal position graphs and vertical

position-time graphs.

6. Investigate how waves behave when the string end is Fixed and Loose with Manual settings. Discuss the behavior with your partners, or think about it on your own. Test your ideas and the write a summary in 2-4 sentences.

LINK to Waves on a String: https://phet.colorado.edu/en/simulation/wave-on-a-string

7. Read to find out what a standing wave is, investigate how to produce one with the simulation and write a procedure that another student could follow to produce a standing wave. Links on standing waves are immediately below:

http://www.physicsclassroom.com/class/waves/Lesson-4/Traveling-Waves-vs-Standing-Waves

http://www.physicsclassroom.com/class/waves/Lesson-4/Formation-of-Standing-Waves

http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Standing-Wave-Patterns/Standing-Wave-Patterns-Interactive

ESSENTIAL QUESTION: How do waves interact?

GOALS: SWBAT...

1. determine what causes the pitch to change

WARM-UP

1. what does high pitch sound like? low pitch?

2. would a high pitch sound have a high or low frequency?

3. Draw a longitudinal wave and a transverse wave.

4. Does sound travel as a longitudinal wave or transverse wave

5. If a compression from one wave interacts with a rarefaction from another wave, what kind of interference occurs? What would this sound like?