Stopped Pendulum

A ball hanging from a rod creating a pendulum that is swinging at a certain height designated by a line on the chalk board.

A ball hanging from a rod creating a pendulum. The string is stopped by a rod and the ball still makes it to the line indicated by the chalkboard line.

PIRA 1M40.15

Materials: 2 Table Clamps, 4 rods, 2 90 degree clamps, string attached to ball

Release a pendulum bob so that it rises to a marked height as shown at left. Release the bob from the same height with a pendulum stop in the path of the pendulum cord and the bob will still rise to the same marked height as shown at right. This is a good demonstration of conservation of energy. Mounting the pendulum and stop supports on the chalk tray of a blackboard as shown allows for convenient marking of height. Note that for some chalk trays this may not work. You may have to use stands on the floor; however, you should still be able to attach a rod clamp to the chalk tray for support.