Steel track with a loop-the-loop and fittings to be held with lab stands.

To demonstrate centripetal force. To show how our theory can be used to correctly make a prediction for the starting height required for the ball to clear the loop without falling.

• Loop-the-loop track
• Small ball (ball bearings or other will do)
• Two lab stands and connectors

Mount the track firmly on the lab stands using the connectors. Before presenting this demo it may be worthwhile to find the minimum height required to clear the loop and mark it with a piece of tape.

When showing the demo, try dropping the ball from a number of different heights. Ask the students to predict how high the ball needs to be- as high as the top of the loop? (Enough potential energy for the height, but not for the kinetic energy, so it reaches the top and falls) or higher? Releasing the ball at 5/2 the height of the loop or higher should result in it going around the loop without falling.