Tennis Ball and Parabola Projection

PIRA: 1D60.50

Overview:

Because gravity is at a constant, when something is thrown up, it follows a parabolic line in the air. We can demonstrate that by projecting a parabola, and then throwing a ball at the right velocity to follow the line on the projection. The mass of the object has no effect on the direction it goes.

Materials:

Two tennis balls, projector, parabola projector sheets

Setup:

Place the projector on a table, and turn it on. Put one of the parabola sheets onto the projector, then adjust the projector so it makes a sharp image and the parabola can be seen on the screen. Place the tennis balls in a convenient spot. Turn off the projector when it is not in use.

How to:

Ask for a volunteer to help. Turn on the projector and toss the light tennis ball between you and the volunteer. Attempt to follow the curve of the parabola. Take the second tennis ball, which is filled with bird shot, and toss that between you and the volunteer. This shows that mass does not have an effect on the path the balls take.

Safety:

The projector can get hot when in use. The heavy tennis ball can cause injury if thrown hard enough.