Chapter 12 Lesson 2 Simple Machines Types of

Chapter 12 Lesson 2: Simple Machines

Types of Simple Machines u A simple machine is a machine that does work with only one movement of the machine. u There are six types of simple machines: lever, pulley, wheel and axle, inclined plane, screw and wedge.

Lever u Lever l a bar that is free to pivot about a fixed point, or fulcrum Resistance arm Effort arm Fulcrum Engraving from Mechanics Magazine, London, 1824 “Give me a place to stand I will move the Earth. ” – Archimedes

Lever u First Class Lever l can increase force, distance, or neither l changes direction of force

Lever u Second Class Lever l always increases force

Lever u Third Class Levers l always increases distance

Pulley u Pulley l l grooved wheel with a rope or chain running along the groove a “flexible first-class lever” F F E L

Wheel and Axle u Wheel and Axle l two wheels of different sizes that rotate together l a pair of Wheel “rotating levers” Axle

Wheel and Axle u input force is applied to the wheel, output force exerted by the axle. u Ex: Doorknobs, screwdrivers, faucet handles

Inclined Plane u Inclined Plane l Slanted surface used to raise objects l h

Screw u Screw l inclined plane wrapped in a spiral around a cylinder

Wedge u Wedge l a moving inclined plane with 1 or 2 sloping sides

Wedge u Zipper 2 lower wedges push teeth together l 1 upper wedge pushes teeth apart l

u Ideal Mechanical Advantage (IMA) l frictionless machine l MA greater than 1 increases force l MA = output force = input distance input force output distance