Weighted Ellipse

PIRA: 1D40.10

Materials: Weighted Ellipse

A cardboard ellipse is weighted so that its center of mass is in a specific area. This is indicated by a dot close to the edge of the ellipse. The other side has a dot in the center of the ellipse. When tossed into the air the body of the ellipse can be seen to rotate about the dot that indicates the center of mass. The dot on the other side will rotate around the center of mass in a circle.

Challange students to try tossing and catching the ellipse by first looking at the center dot, and then the center of mass dot. It is much easier to catch the disk when watching the center of mass because the eyes have something to focus on whereas the central dot moves too much.