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Simple Machines

Simple Machines

You must have noticed workers loading a truck or heavy loads up the building. Do you know what makes their works simpler?


A device that helps us lift heavy loads, change the speed of the motion or change the direction of a force is known as a simple machine. Simple machines are the tools that help people work faster and better.

There are various simple machines around us used for various purposes. Let us look at some of them.


  • Inclined Plane: It is a sloping flat surface along which a load can be easily pushed or pulled.

  • Wedge: It is a double inclined plane that helps us to tear apart the solid objects.

  • Wheel and Axle: It consists of two cylinders of different radius joined together such that if one is made to rotate the other one also rotates.

  • Pulley: It is a circular disc having a groove in its edge and capable of rotating about an axle passing through its central axis.

  • Lever: It is a machine with a rigid bar which can rotate about a fixed point or a fixed line. It has a fulcrum, an effort arm, and a load arm.

We will be further discussing them in detail.

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.


Beam Balance


Mechanical advantage of a lever of first order

In case of First order lever Mechanical advantag…

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