Purpose:Demonstrate stable equilibrium when supported at center-of-mass
A brass barbell with two different disc-shaped masses, one on each end, is supported by a stand at its center of mass.
Compare this to lifting up an asymmetrical barbell in the gym with one hand, and finding that it is the easiest to hold it at its center of mass.
Ask students to make predictions:
• What would happen if the brass barbell is shifted so that the heavier mass is closer to the middle?
• Would the barbell rotate and if so, in what direction?
• Would it remain on the stand?