Have you ever managed to move something with just the power of your mind? Well, that’s because it takes work to move something, and while your mind is super powerful, it cannot do physical work to move an object. You what it can do though? Tell your muscles what to do so you can do work on an object.

Before we get into work though, I just want to mention mass and weight. They are not the same thing! Did you know that? When we talk about somethings mass, we are talking about how many atoms it is made of – so if something has a mass of 15kg, and we know what types of atoms are in that object we could work out how many atoms there are in that object. Weight is how much gravity is pulling that object down. Things that have more mass tend to have a bigger weight because gravity can do work on more atoms.

If you go into space, then your weight will drop to 0, but the number of atoms you are made of will stay the same so your mass will not change. Remember the difference!

In order for energy to change (including lifting an object) from one store to another, **work** needs to be done. Work is done on an object when a force acts to move an object in the direction of the force, even if movement does not take place.

Work is essentially the amount of energy that has changed form. This can be calculated using the following formula:

work = force × distance travelled

The force is measured in **Newton** (N) and the distance in metres (m). The unit for work is **Joules** (J).

This equation tells us that if you increase the force or the distance an object travels, then you will increase the work as well.

Let's have a go at an example:

Sarah move an object that weighs 500N 2m, how much work has she done?

**1 – highlight all of the numbers.**

Sarah move an object that weighs __ 500N 2m__, how much work has she done?

**2 – write down what they mean:**

Weight (force) = 500N

Distance = 3m

**3 – put them into the equation**

Work done = 500 x 3

**4 – do the sum in your calculator and write down the answer:**

Work done = 15000J.