Friction & Pressure

1. Friction & Pressure

2. Definitions • Friction – the force that resists the sliding between two surfaces • Static Friction – friction that must be overcome to get an object of move • Sliding Friction – caused when two surface rub against each other • Rolling Friction – allows a round object to turn against another object without slipping

3. Fluid Friction – caused by an object trying to pass through a fluid like water or air • Lubricant – anything that reduces the friction between two objects • Pressure – the force per unit area that is applied on the surface of an object • Pascal – unit for measuring pressure in Newtons per Meter squared.

4. Balanced Forces – forces acting on an object in equal and opposite directions • Unbalanced Forces – forces acting on an object in opposite but unequal directions • Buoyancy – refers to an objects ability to float on a liquid or rise in a gas

5. Principles of Pressure • Archimede’s Principle – the buoyant force on an object is equal to the weight of the fluid it displaces. • Pascal’s Principle – when a force is applied to a fluid in a closed container, the pressure in the fluid increases everywhere by the same amount. • Bernoulli’s Principle – when a fluid increases speed the pressure it exerts decreases.

6. New Formulas • Pressure Pa = N/m2 • Area • Square/Rectangle = Length * Width • Triangle = 1/2 * Height * Length • Circle = πr2