Simple Machines

Simple Machines

A lever is a simple machine. It consists of a rigid bar, which is capable of turning around a pivot, which is also called a fulcrum. Generally, we use a rod, which can rotate freely about the fulcrum.

For lever, we generally use two more terms apart from the general terms used for all the machines.

• Load Arm— It is the distance between the fulcrum and the point where the load is applied.

• Effort Arm — It is the distance between the fulcrum and the point where the effort is put.

The working of all levers is based on a common principle, which is called principle of lever.

Principle of lever

Load × Load arm = Effort × Effort arm

If we rearrange the equation, we obtain

Therefore, the mechanical advantage of a lever is nothing but the ratio of the length of its effort arm to the load arm.

Different Types of Lever

Levers are classified into three types depending upon the positions of load, fulcrum, and effort.

Lever of first order

When the fulcrum is situated between load and effort, we call it a lever of first order. For example, beam balance, a crowbar, a seesaw.

Crowbar	Beam Balance	Seesaw

Mechanical advantage of a lever of first order

In case of First order lever Mechanical advantage can be equal to 1 or greater than or less than 1.It depends on the position of the fulcrum between effort arm and load arm.In case of levers of first order, we try to keep the load arm smaller than the effort arm i.e., effort arm > load arm. Therefore, a big load can be shifted by using small effort with the help of a lever of first order. As the effort arm is larger than the load arm,

When effort arm is less than load arm then mechanical advantage is less than 1.When Effort arm is equal to load arm then mechanical advantage is equal to 1.
 

Lever of second order

When the fulcrum and effort are situated at the two opposite ends of the lever and a load is placed in between them, we call it a lever of second order. For example, a nutcracker, a wheel-barrow, etc.

Wheel-Barrow	Nutcracker

Mechanical advantage of a lever of second order

In case of levers of second order, the load arm is always smaller than the effort arm i.e., effort arm > load arm. Therefore, a big load can be shifted by using small effort with the help of a lever o…