Buoyancy

physics · water · forces

Pressure pushes up. Water pressure is stronger deeper down because there is more water pushing down from above. This means the bottom of a submerged object feels more pressure than the top, creating an upward push.

The upward force. Buoyancy is the net upward force that happens when pressure from below is greater than pressure from above. This force pushes floating things up instead of letting them sink.

Equal to displaced fluid. The buoyant force on an object equals the weight of the fluid that the object pushes out of the way. If you fully submerge a 1-kilogram block, the buoyant force equals the weight of 1 kilogram of water.

Works in any fluid. Buoyancy happens not just in water but in any fluid, including air. This is why helium balloons float upward through the air.