Density Rod

The density rod, crafted from machined aluminum, floats in cold water but sinks in warmer water due to density differences.

When placed in hot water, the rod initially sinks; however, once the water temperature falls enough to increase its density beyond that of the rod, it ascends to the surface. 

This is a simple physics experiment to stump your know-it-alls.

0.65" x 3.5"