Purpose: To show the ease with which you can find the center of gravity and show that it is the center of rotation.

A few irregular plywood shapes with holes around their edges, a plumb line, brass pivot connected to a stand, and a dry erase marker.

Place the brass pivot through any hole on the edge of the geometric shapes and let it hang from this point. Now tie the plumb line to the brass bar and mark off a line with a dry erase marker along the thread. Repeat this for other holes. Highlight the point of intersection with a red dot.

Play catch with the geometric shape to show that the center of gravity follows a parabolic path.

Be careful to catch the objects so they don't hit the ground. The are made of a material that will not withstand too many impacts with the floor.

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