SIMPLE MACHINES THE LEVER FAMILY simple machines One

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: l simple lever (3 types) lpulley l wheel and axle l simple inclined plane l wedge l 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.

Chapter 12 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