• A lever is a rigid rod arranged in such a manner that it can move freely around a fixed point.
• It consists of three parts.
Figure 44: A rod, fulcrum, load and effort make up lever
• This is the fixed point around which the rod moves.
• It is the object on which work is to be performed.
• It is the force that needs to be applied on the rod in order to perform a task.
• Based on the position of three parts of a lever, it can be classified into the following three types.
• Levers in which the fulcrum is located between the load and the effort are called first-class or class one lever.
Figure 45: A pair of scissor is a first class lever, a barber uses scissor to cut hairs of a person
Few more examples:
Figure 46: See-saw, weighing machine, clipper, plier are all first class levers
Figure 47: Corkscrew bottle opener, hand pump
Figure 48: A boy is holding a crow bar which acts as class one lever, a hammer and a can opener is a first class lever
• Levers in which the load is located between the fulcrum and the effort are called second-class or class two levers.
Figure 49: A wheelbarrow, a dumper (dump truck), a nutcracker- all are class two levers
Figure 50: Bottle openers, a paper cutter, door of a microwave oven are all second class levers
Figure 51: A water/chemical sprayer, OTG door (oven toaster griller), a fire extinguisher - all are second class levers
• Levers in which the effort is located between the fulcrum and the load are called third-class or class three levers.
Figure 52: A fishing rod, a stapler
Figure 53: Traffic barrier, towing machine
Figure 54: A shovel, pair of tongs, a girl is holding a pair of tongs to cook some food for herself
Figure 55: A girl swinging, a man digging soil
Figure 56: A man is hammering a nail into wood; a girl is sweeping on a floor so her broom acts as a class three lever
Figure 57: A clearer image of pair of tongs used to hold food, the cap of dustbin - All are third class levers