1J11.30 Instability in Flotation

A top-heavy styrofoam slab is unstable when floating; after it has keeled over and it is bottom-heavy, it will be stable as it floats.

A styrofoam block floats in a rectangular glass aquarium half-full of water. A piece of lead wraps gently around one side of the of the styrofoam block (bending around from one short side to the other). Additional thin lead sheets can be tucked under the metal 'wrap'. The styrofoam block can be carefully positioned lead-side-up in the tank. However, a gentle prod will cause the block to flip. Once lead-side-down, the block will float and bob regardless of prodding.

Location: Aquarium o2-2, Styrofoam Slab with Lead Weights B2-2