SIMPLE MACHINES

THE LEVER FAMILY

simple machines One of six basic types of machines which are

basis for all other forms of machines.have a rigid arm and a fulcrum.

six types divided into two families.lever family: inclined plane family:

simple lever (3 types)

simple inclined plane

pulley wedge

wheel and axle screw

FIRST CLASS LEVERS

fulcrum located between points of application of input and output forces.

seesaw

SECOND CLASS LEVERS

• fulcrum is at one end of arm and input force is applied to other end.

• wheelbarrow

THIRD CLASS LEVERS

• multiply distance rather than force. • have a mechanical advantage of less than 1.• arm

PULLEYS

modified levers.point in middle of a pulley is like

fulcrum of a lever.single, fixed pulley has a m. a. of 1.block and tackle: Multiple pulleys working together

PULLEYS

WHEEL & AXLE

a lever or pulley connected to a shaft.steering wheel of a car, screwdrivers, and

cranks

THE INCLINED PLANE FAMILY

multiply and redirect force.turns small input force into large

output force by spreading work out over a large distance.

SIMPLE INCLINED PLANE

Changes both magnitude & direction of force

WEDGE

Functions as two inclined planes back to back.

Turns single downward force into two forces directed out to sides.

SCREW

an inclined plane wrapped around a cylinder.

COMPOUND MACHINES

machine made of more than one simple machine

Examples :scissors • two first class levers joined

at a common fulcrum

car jack • combination of lever with a

large screw

Chapter 12