A
roly-poly toy,
round-bottomed doll,
tilting doll,
tumbler or
wobbly man is a
toy that rights itself when pushed over. The bottom of a roly-poly toy is round, roughly a
hemisphere. Many roly-poly toys are hollow, with a weight inside the bottom. They have a
center of mass below the center of the hemisphere, so that any tilting raises the center of mass. When such a toy is pushed over, it wobbles for a few moments while it seeks the upright orientation, which has an
equilibrium at the minimum
gravitational potential energy.