4.1.2.P26

Instagrammer Dexton4 (Dexton Crutchfield) uploaded this video of himself dunking a basketball:

The video should play in most browsers (you may have to right click to show controls), but if it doesn't, you can play the downloadable version below in most media players or follow the link above to his Instagram.

Here is a version of the video formatted to load into ImageJ. (The web version will not play in ImageJ due to its compression.) Follow that link and click the "Download" tab above the page to save the file to your computer.

For the questions below, explain how you got each of your answers.

1 - Crutchfield's Instagram says he is 5'8" tall. Approximately how far did he jump?

2 - Approximately how high is the rim?

3 - The video is about 400 frames long and 13 seconds long. (Ignore ImageJ's readout of the time; it is generally incorrect unless you specially fix it.) Find the acceleration of the ball (using the video's slowed-down time) after it bounces, but before Crutchfield touches it.

4 - In real life, the ball had a downward acceleration of 10 m/s² during that time. According your answer from the previous part, by what factor is the video slowed down?

5 - How fast was Crutchfield running in real life just before he jumped?

6 - Estimate the average force between Crutchfield's shoe and the ground as he lands. Please explain your reasoning. You don't need to do motion tracking here, but you may if you like.

7 - Describe where the ball is, relative to Crutchfield's head, during the jump. How does that relative position change throughout the jump? How is this motion related to where his hand is during the jump? Your answer can be qualitative here.

Mark Eichenlaub 9/19/17