Coin on Rotating LP: Application Experiment


To determine the maximum coefficient of static friction by observing where a coin placed on a rotating LP slips, and test this measurement against another method.

Prior Knowledge

  • Circular motion
  • Newton's laws
  • Friction force, static friction force

Description of the Experiment

A dime is placed at various distances from the centre of the spinning disk until it slips. Use the data in the video to figure out the maximum coefficient of static friction between the disk and the coin. The disk is then slowly raised so that it forms a larger and larger angle with the horizontal until the coin slips. Use this method to obtain a second measurement of the maximum coefficient of static friction. Compare the results of both methods.

Addtional Information

Decide how you are going to determine the angular speed of the record.

Youtube movies can be stepped frame by frame using the , and . keys on your keyboard. If you want to download the movie to your computer, right-click or control-click HERE.


  1. What physics explanations/relationships did you use to find the maximum coefficient of static friction?
  2. Did the assumptions that you made allow you to use these explanations/relationships?
  3. Did the results from the two experiments match? If not, how do you need to modify your assumptions to change the mathematical procedure?
  4. Make a list of sources of uncertainties in determining the maximum coefficient of static friction in each experiment. How can you minimize the uncertainties?