Buoyancy

Principles Illustrated: Buoyancy, Displacement, Pressure

Location: Cabinet D, Shelf 3

A ketchup packet has a small bubble of air trapped in it. When you squeeze the outside of the bottle, you increase the pressure inside the bottle. This will compress the air inside the packet, which changes the overall density of the packet. When the air is compressed enough, the density of the packet will be greater than the density of the water in the bottle, and the packet will sink. When you release the pressure on the outside of the bottle, the air in the packet will expand, increasing the buoyancy of the packet, and the packet will rise to the top.