Levers
Parts of a lever
Third class levers
First class levers
Effort or force
Load
Fulcrum
Bar or beam
A lever makes work easier by both increasing your input force and changing the direction of your input force.
The beam is simply a long plank. It may be wood, metal or any durable material.
The beam rests on a fulcrum (a point on the bar creating a pivot).
When you push down one end of a lever, you apply a force (input) to it.
Second class levers
The lever pivots on the fulcrum, and produces an output (lift a load) by exerting an output force on the load.
In a first class lever, the fulcrum is located between the load and the effort.
If the fulcrum is closer to the load, then less effort is needed to move the load a shorter distance. If the fulcrum is closer to the effort, then more effort is needed to move the load a greater distance. A teeter-totter, a car jack, and a crowbar are all examples of first class levers. First class levers are very useful for lifting large loads with little effort.
In a second class lever, the load is located between the effort and the fulcrum.
If the load is closer to the fulcrum than the effort, then less effort will be required to move the load. If the load is closer to the effort than the fulcrum, then more effort will be required to move the load. A wheelbarrow, a bottle opener, and an oar are examples of second class levers.
In a third class lever, the effort is located between the load and the fulcrum.
If the fulcrum is closer to the load, then less effort is needed to move the load. If the fulcrum is closer to the effort, then the load will move a greater distance. A pair of tweezers, swinging a baseball bat or using your arm to lift something are examples of third class levers. These levers are useful for making precise movements.
Examples of Class One Levers include seesaws, boat oars and crowbar.
Examples of Class Two Levers include wheelbarrows.
An example of Class Three Lever is a garden shovel.