SIMPLE MACHINES

WHAT IS LEVER ?

Lever isa)A simple machineb)Enables small effort to overcome a

heavy loadc) Can be used to lift heavy objects d)Makes work easier A lever is a simple machine which turns about a fixed point called the FULCRUM, when a force called the EFFORT is applied to overcome a resisting force known as the LOAD

LEVER

WEDGEWHEEL AND AXEL

6 TYPES OF SIMPLE MACHINES

SCREW

PULLEY

INCLINED PLANE

WHAT IS LEVER ?

A lever has 3 parts a)Fulcrum - the turning point or pivot

b)Effort - the force applied to overcome a resisting force called the load

c)Load - the resisting force exerted by an object

SIMPLE MACHINES

FIRST CLASS LEVER

Relative position of F ,E and L - F between E and L Common characteristics - Small force is used to move a large loadEffort moves through a longer distance than the loadEffort is further from the fulcrum than the load

Common devices Claw hammer Pliers Scissors Crowbar

SECOND CLASS LEVER Relative position of F , E and L Second class lever L between F and E Common characteristics - Small force is used to move a large load Effort moves through a longer distance than the load Effort is further from the fulcrum than the load

Common devices Wheelbarrow Bottle opener Paper cutter Nutcracker

THIRD CLASS LEVER Relative position of F ,E and L Third class lever E between F and L Common characteristics - Large force is used to move a small loadLoad moves through a longer distance than theeffortLoad is further from the fulcrum than the effort

Common devices Fishing rod Broom Ice tongs Human arm

WHAT IS THE MOMENT OF A FORCE?

When we loosen a bolt using a spanner, a force that is applied has a turning effect on the spanner. This turning effect of force is known as the moment of force

WHAT IS THE MOMENT OF A FORCE?

The moment of a force is the turning effect of the force

The moment of a force is defined as: Moment of a force (N m)=Force (N) x Perpendicular distance from the pivot to the force (m)

The moment of a force can be increased by: Increasing the size of the force Applying the force at a further distance from

the pivot

PRINCIPLE OF MOMENTS IN A LEVER

The effort and the load produce opposing moments

When the lever is in EQUILIBRIUM , the sum of the anticlockwise moments about a point is equal to the sum of the clockwise

PRINCIPLE OF MOMENTS IN A LEVER

When the lever system is balanced Anticlockwise moment = Clockwise moment

Load (N) x Distance of load from fulcrum (m)=

Effort (N) x Distance of effortfrom fulcrum (m)