• Transverse and Longitudinal Waves, length 5:47

• Wave Amplitude, length 3:15

• Wave Period and Frequency, length 4:51

• Wavelength, length 3:22

• Wave Speed, length 6:09

• Wave Reflection, length 4:37

New material:

• Transverse and Longitudinal Interference, length 2:54

• Wave Superposition (aka Interference), length 4:39

• Speed of wave in a string, length 8:13

• Paul Anderson, Simple Harmonic Motion, length 8:04

• A Plus Physics, Simple Harmonic Motion, length 7:41

• Khan Academy, series of videos on SHM

The only SHM equation in the AP Equation sheet is x = A cos(2 pi f t). My experience is that you will be confused. You have to persevere and not give up.
That equation can best be understood from the image below.

That image calls the radius X, which is the radius of the circle. The SHM equation calls the radius A (for amplitude). That represents the maximum distance an object is displaced from the equilibrium position along a horizontal line. We are using a point moving around the circle to represent the position of the object moving along the horizontal line, by analogy. Think of the shadow that would be cast by the point moving around the circle on the horizontal line. See the diagram below:

Back to the equation:
x = A cos (2 pi f t). It starts out as x = A cos (theta). (See the top image) But we know theta = omega t (d = vt in rotational kinematics). And omega = 2 pi/T , or 2 pi f. Put it all together and we get x = A cos (theta) = A cos (2 pi f t)
Check out these notes:
Simple Harmonic Motion
Flipping Physics SHM
Lumen Physics, Uniform Circular Motion and SHM
Periodic Motion, Lumen Physics, strongly recommended by James (Thank you)
Circular motion animation analogy
If you have any questions, email me.

Go to Speed of Waves on a String Lab.
Follow the procedures for parts 1 and 2. Ignore "Part 3: Live Part." You will be gathering data to fill out the data table shown. You will then create four (4) graphs:

Graph 1) Linear density vs. speed (where tension is the same on all strings); and

Graph 2) Tension vs. speed (where mu (linear mass density) is the same for all strings).
Those two graphs should be curves. I then want you to linearize both graphs. This requirement is NOT in the online instructions.

Graph 3: A line graph using the first data table of linear density and speed. You need to know how to label the axes (and then calculate the new values to be plotted) so that you end up with a line graph.
You must then show how you can use the slope of the graph to find the tension in each string. Remember, you had to make the tension equal in each string before collecting the data for the first data table.

Graph 4: A line graph using the second data table of tension and speed. You need to know how to label the axes (and then calculate the new values to be plotted) so that you end up with a line graph.
You must then show how you can use the slope of the graph to find the linear mass density (mu) in each string. Remember, you had to make the mu equal in each string before collecting the data for the second data table.

You must prepare a lab report in electronic form that can be sent to me. The graphs can be constructed using a spreadsheet program such as Excel or Google Sheets. There is also a graphing tool that comes with the lab exercise. You may also do the graphs by hand and embed a picture of the graphs in your electronic lab report. So you have multiple options as to how you create the graphs. If you need help using a spreadsheet program to make a graph, research the internet. Here are some resources on graphing with spreadsheet programs:

• How to create a graph in Excel
• Creating line graph in Google Sheets

• Video discussion of sample problem calculating speed of wave in string, length 3:36
• Ms. Twu discusses speed of wave in string problem, length 4:58

NEWS FLASH: Through the generosity of the New Jersey Center for Teaching & Learning, a self study program in AP Physics 1 and 2 has been made available to you. I am just learning what the resource provides and how I might use it for you. But you may immediately register and begin using it however you see fit. To register, follow the instructions which can be found here.

If you have any questions, email me.