All Textbook Topics - Forces and Motion - Friction, Lubrication and Viscosity

Friction, Lubrication and Viscosity

Did you know that friction is almost always the reason why objects slow down? Friction is another staple of forces and motion ideas. Friction is encountered almost everywhere, but can be reduced by lubricating moving parts, like the chain on a bike.

Textbook Learning Objectives
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1Friction is a force that opposes motion
2Friction acts in the opposite direction to motion
3Friction slows moving objects down
4Friction causes heating and wearing
5Dynamic friction is a force applied to an object moving over a surface, by the surface, acting in a way to slow the object down
6Static friction is a force applied to an object by a surface when you try to move the object. The object will only start to move once the force applied is greater than the static friction.
7Lubricants reduce friction
8Viscosity is an expression of how much internal friction there is in a fluid
9Fluids which are highly viscous make it more difficult for objects to move through them as they apply more friction
10Fluids which have a low level of viscosity have less friction so objects can move through them more easily