1M40.20-Loop ball track

1m4020_loop_ball_track 1m4020_loop_ball_track_2

Video: Watch this demo

Instructor Video

MIT Demo video

Description: This apparatus can be used to show the requirements for a ball to travel in a loop successfully:
The centripetal force on top will be at least as large as the force of gravity on the ball (normal force is just barely zero at the critical velocity). You can calculate the minimum release height from conservation of energy*.


  • Loop track
  • Ball. NOTE: A ball with a rough surface works best because it will roll, and will thus lose less energy to friction.
  • Possibly another ball, so that one has a smooth surface (will slide) and one a rough surface (will roll).

Setup Procedure:

  1. Check that the balls do in fact make it around the loop from the heights marked on the track.

Demonstration Procedure:

  1. Drop the ball(s) from various heights to demonstrate the requirements for the ball to make it around the loop without falling off*.

Tips: The track is labeled on one side where the minimum release height is.

Warning: Calculations may not come out correct because the ball does transfer a considerable amount of energy to either rotational kinetic energy, sliding friction, or both.