Unit 7
Pressure and fluids.
Force over an area: gas pressure, pressure with depth, floating, flow in a narrow pipe, and surface tension.
Before this unit
The unit, lesson by lesson
Lessons
4 lessons · 29 practice questions · about 2 hours
Pressure
Pressure is force spread over an area: a gas that pushes because its particles strike the walls, Boyle's law, particles that speed up as the square root of temperature, the gas law, and pressure that grows with depth under water.
Floating and buoyancy
Why things float or sink: density, the buoyant force and Archimedes' principle, what share of a floating cube is under water and why it doesn't depend on size, what holds up a cube that has sunk, and steel that floats on mercury.
Flow and Bernoulli's principle
Water in a pipe that narrows: continuity and water that speeds up in the throat, pressure that falls where the water is fast, Bernoulli's equation, a pressure drop that grows as the square of the flow, air drawn in, and a perfume atomiser.
Surface tension and capillarity
A liquid that climbs a thin tube with no pump: surface tension and the glass's pull, why a tube half as wide holds a column twice as tall, Jurin's law, mercury that sinks, and why capillary action alone can't lift water to the top of a tree.