Levers: Simple Machines - Levers- EnchantedLearning.com.
The lever is a simple machine. All levers have an applied force, a fulcrum and a load arranged on a rigid bar. The arrangement of these elements determines the type of lever: first, second or third class. Examples of levers in everyday life include seesaws, nutcrackers, mops, brooms and golf clubs.
First class levershave the pivot positioned between the effort and the load. Common examples of first class levers include a seesaw, a crowbar, pliers, and scissors. Second class levershave the pivot and the effort at opposite ends and the load positioned between the two.
The class of lever depends on the location of the load, force, and fulcrum. Some examples of levers include more than one class, such as a nut cracker, a stapler, nail clippers, ice tongs and tweezers. Other levers, called single class levers include the claw end of a hammer.
A good example of a first-class lever is a child's see-saw. Levers are simple machines — apparatuses composed of few or no moving parts that make performing a task easier by one or more of four methods: Transferring where the force is applied to where it acts.
Together, the wheel and the axle make a simple machine. We can see such an arrangement in cars, sewing machines, egg beaters, bicycles, the potter’s wheel etc. Other examples are a water wheel, a windmill, gears, doorknobs, faucet handles, and steering wheels.
Lever is a simple machine containing a beam pivoted to a fixed end by fulcrum. The amount of force used internally by this simple machine is called as mechanical advantage of lever. There are three classes of levers: first, second and third. The ratio of the effort arm and load arm is the MA of lever.
Class-1 levers have the fulcrum situated between the load and the force. A playground teeter-totter is an example of a class-1 lever. Class-2 levers have the load situated between the force and the fulcrum. A wheelbarrow is a common example of a class-2 lever, with the fulcrum at the wheel, the force at the handles and the load in the barrow.