Machines come in two kinds — Simple Machines and Complex Machines.

Simple Machines

A simple machine is a tool, device, or object with few moving parts that help us do work. Simple machines have been in use for a very long time. Early humans used simple machines to push, pull, lift, divide, and crush things. They used simple machines to row rafts over water, build houses, split firewood, and carry heavy items from place to place. Today, there are simple machines everywhere and all around us.

There are six types of simple machines — the inclined plane, the wedge, the screw, the lever, the wheel and axle, and the pulley. These six have specific features and do unique jobs, even though some may work in similar ways. Some simple machines may be a combination of simple machines.

Important:
Simple machines, unlike complex ones, do not work on their own. They only increase the pull or push (force or effort) that a person uses, increase or decrease the distance, or change the direction of a movement so that more work is done. They can:

• transfer a force from one place to another
• change the direction of a force
• increase the magnitude of a force
• increase the distance or speed of a force

Features of a simple machine

• They do not use electricity
• They have one or fewer moving parts
• They give us a mechanical advantage
• Even though they make work easier for us, they still need input (force or effort) from a person.
• They make tough jobs easier by changing the force, direction, or speed of a movement.

Complex Machines
Simple machines are different from complex (or compound machines). Complex machines, like trucks, wagons, or bicycles, use many moving parts. They combine many simple machines such as levers, pulleys, and gears to get work done.
Now, we shall look at each example of a simple machine.