Closer examination revealed that the object had gear wheels embedded in it – as though it was some kind of ancient clock. It soon became known as the Antikythera Mechanism but its internal structure and purpose remained mysterious for decades.

Later investigations using X-rays uncovered thirty interlocking gears and inscriptions of the ancient Greek words for “sphere” and “cosmos”. These discoveries suggested it was a sophisticated machine designed to track the motions of the planets and the phases of the moon. The ancient Greeks could use this information to work out when to hold the Olympic Games and other religious festivals. They could even predict astronomical events such as eclipses.

Scientists and historians were shocked. Nobody could believe that such a complex machine was made 2000 years ago!

And when you think about it, it is amazing that an ancient civilization managed to build an ingenious time-keeping device out of a small collection of simple gears.

If you try to open a tin of drinking chocolate with your bare fingers then you're likely to just get sore fingers. But when you wedge a teaspoon under the lid and push down on the handle, the lid opens easily. Why is this?

The answer lies in a simple mechanical principle discovered 2000 years ago by the Greek mathematician, Archimedes.

If you had a long crowbar you could use a small rock as a fulcrum and then use the lever principle to shift the boulder with less effort. As shown in the diagram on the right, the amount of effort force you need depends on the length of the effort arm compared to the length of the resistance arm.

Mechanical advantage is a measure of how much the effort is reduced and it depends only on the lengths of the two arms:

For example, if the length of the resistance arm is 0.5 m and the length of the effort arm is 2 m then:

With this mechanical advantage you could use a quarter of the effort force needed to lift the boulder without a lever. The downside is that you need to apply the force over a larger distance, as shown in the diagram.