Efficiency

Imagine you're trying to push a really heavy box across the floor. It's tricky because of friction, which is a resisting force that opposes movement.

Now, what if you put the box on a dolly with wheels? Wheels reduce friction and make movement easier.

Here, the dolly acts as a simple machine, helping us do work more efficiently. All machines work in a similar way, but they also experience friction.

Because of this, no machine can use all the energy we put into it without losing some along the way.

Efficiency measures how well a machine performs its task. It tells us how much of the work we put in actually contributes to the machine's function.

For example, suppose you push a box up a ramp and put in 7,500 joules of work, but only 6,700 joules are used to move the box.

To find the efficiency of this ramp, divide the useful work output of 6700 joules by the total work input of 7500 and multiply it by 100%, giving an efficiency of 89.3%.