Buoyancy
The key idea
A body immersed in a fluid experiences an upward buoyant force associated with the pressure variation over its surface. Archimedes’ principle relates it to the weight of displaced fluid.
Why it matters
Floating is therefore a balance problem involving the object, gravity and the displaced fluid—not a mysterious property of 'light' materials.
A picture to remember
Floating is therefore a balance problem involving the object, gravity and the displaced fluid—not a mysterious property of 'light' materials.