Chapter 12 Lesson 2: Simple Machines. Types of Simple Machines AA simple machine is a machine that...

Chapter 12

Lesson 2: Simple Machines

Types of Simple MachinesA simple machine is a

machine that does work with only one movement of the machine.

There are six types of simple machines: lever, pulley, wheel and axle, inclined plane, screw and wedge.

LeverLever

a bar that is free to pivot about a fixed point, or fulcrum

“Give me a place to stand and I will move the Earth.”– Archimedes

Engraving from Mechanics Magazine, London, 1824

Effort arm

Resistancearm

Fulcrum

LeverFirst Class Lever

can increase force, distance, or neither

changes direction of force

r

e

LL

IMA

LeverSecond Class Lever

always increases force

r

e

LL

IMA

LeverThird Class Levers

always increases distance

PulleyPulley

grooved wheel with a rope or chain running along the groove

a “flexible first-class lever”

F

F

E

L

Wheel and AxleWheel and Axle

two wheels of different sizes that rotate together

a pair of “rotatinglevers”

Wheel

Axle

Wheel and Axle input force is applied to the

wheel, output force exerted by the axle.

Ex: Doorknobs, screwdrivers, faucet handles

Inclined Plane Inclined Plane

Slanted surface used to raise objects

hl

ScrewScrew

inclined plane wrapped in a spiral around a cylinder

WedgeWedge

a moving inclined plane with 1 or 2 sloping sides

WedgeZipper

2 lower wedges push teeth together1 upper wedge pushes teeth apart

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

input force output distance