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How do machines work?

Pulleys reduce the amount of effort needed to raise and lower the crate from the lorry.Machines are designed to make work easier and quicker to complete. They use forces to do different jobs. Even complex machines are made up of a few kinds of simple machines: pulleys, levers, wedges, screws, wheels and axles, and slopes. Here, as shown in this illustration on the right, a crate of apples is unloaded using a pulley (it is easier to pull down on a rope than to pull up). The apples are checked before the crate is loaded into a van. This sequence shows how machines can be used to carry out a simple job.


The lid of the crate is prised open using a lever. The edge of the carton acts as a fulcrum.

A lever is a bar that rests on a point called a fulcrum. As you press down on one end, the other end lifts the load. The closer the fulcrum to the load, the smaller the effort needed.

One of the very earliest "machines" was a hand axe. The first hand axes date back to about 1.6 million years ago. They were made by chipping a piece of flint to form a wedge.

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