Fluids
A fluid is any substance that flows — both liquids and gases.
- Viscosity is a fluid's resistance to flowing; density is its mass per unit of volume.
- An object floats when the buoyant force equals its weight.
- Fluids exert pressure, and hydraulic systems use this to multiply force.
An object floats if it is less dense than the fluid around it, and sinks if it is denser.