Set up time
Physics and Science Concepts
Mount apparatus to ring stand using clamp, adjust until apparatus is horizontal, cock the apparatus spring, and place the masses (one at the end of the apparatus and one on the bar that extends from the apparatus), release, and one ball will fall from rest (hung on the rod) while the other ball is struck by the rod and has an initial horizontal velocity. The balls should hit the table at the same time, which can be heard clearly by students. Repeat by cocking spring to different compression. Repeat by clamping apparatus at a different height to show that height has no effect on the simultaneity of the fall.
Once spring is compressed, do not put hands in front of the end of the rod.
An apparatus is used to launch a ball and drop a ball simultaneously to show that they hit the table at the same time.