# Stretching things and Hooke’s law

If you get hold of a rubber band and pull it you are using a force on it. That force makes the rubber band get longer – it stretches. The greater the pull the longer it gets. In other words a bigger force makes the rubber band stretch more.

The bigger the force the bigger the extension

Instead of a rubber band we could use a spring like the one in the picture. We can put a force on the spring by hanging a weight from the end of the spring.

As more and more weights are hung on the springs its length will change. The drawing shows what happens when equal weights are added to the spring. The spring is gets longer and longer.

We call the difference in length between the new length and the length without any weight on the spring the extension of the spring.

### Hooke's Law

The more force that is put on to a piece of elastic or a spring the more it will stretch. The length increases by the same amount every time the force was increased by a fixed amount.