Introduction: AP Physics Capstone Project: Reese Wills

Hi! This is my AP Physics capstone project. Today I will be showing how to make this craft that demonstrates a very important characteristic of waves in physics - that wave speed does not change through a medium no matter how much force is applied to the end of the ball. I hope you enjoy it!

Step 1: Garner Resources

First, you will want to collect the following materials:

- 1 roll of Duct Tape (any color works, but I have found that brighter colors make the demonstration less dull)

- 1 pack of clay

- 15 kabob sticks

- 2 one gallon jugs of water


- A small scale

- A ruler

- 2 large textbooks

Step 2: Roll the Clay Into 30 Small Balls of the Same Weight

These will be used to place on the ends of the kabob sticks, and in order for this demonstration to work, the balls need to be almost exactly the same weight. I recommend using a scale to weight out balls of exactly the same weight. The weight that the balls need to be is irrelevant, as long as the weight is equal the demonstration will work, but smaller balls are easier to make and use in the experiment.

Step 3: Add the Clay Balls Onto the End of the Kabob Sticks

Put the kabob sticks into a line as seen in the picture above.

Step 4: Add Tape to the Kabob Sticks

This step is very important. Add duct tape to the exact center of the kabob sticks (this is where the ruler might come in handy). Put tape on both the top and the bottom of the kabob stick as to make sure that the tape does not fall of and it is very strong. Any color tape will work, as long as it is strong and will hold. Here I chose to use grey, but later I added a strip of red tape.

Step 5: Tape Your Kabob Sticks to the Top of Your Water Bottles

Using the duct tape, tape the string of kabob sticks to the top of the water bottles. They should not be touching the ground, and the string tension should be high. This shows another property of waves, that the tension of the medium has a large factor in how fast the wave speed is.

Step 6: Add Color to Your Demonstration

Add a strip of color for fun!

Step 7: Finished!

Now you are finished! Hit one of the clay balls on the kabob sticks on the end and watch your wave! As you can see the force that you hit the clay ball with only affects the amplitude of the wave, not the wave speed! This can help people to learn that a wave's medium is the only factor in determining wave speed. This relates directly to the fundamental wave equation, v = f(lambda). Normally, people would think that changing frequency or wavelength would affect the wave speed, but really the two variables only affect each other, while wave speed is left alone until a change in the medium occurs.

Step 8: Problems

I encountered three main problems while completing this demonstration. First, it was hard to make the clay balls the same weight so that the demonstration worked. To fix this, I weighed each ball with a weight. Second, it was hard to tape the string of kabob sticks to the top of the water bottles, but with enough effort the conflict resolved itself. Lastly, the water bottles continued to fall in on each other, to fix this I added more weight to the water bottles with text books.

Step 9: Sources

Thanks to Raika, Eric, and youtube for giving me the idea to make this. Here is a link to the youtube video that did the same: I also want to thank Ms. Monticue for allowing me to remake my project and teaching me all about the physics of waves. I also want to thank my parents for providing the financial backing in my project. Lastly, I want to thank my prom queen Jena for inspiring me to work harder each day.