# Newton units

#### Back to Physics Grade 9/10

The unit measurement for a force is called the *newton*, in honour of the famous physicist Sir Isaac Newton. One newton or N is the amount of force needed to accelerate a mass of 1 kg at the rate of 1 m/_{s2}.

We'll learn more about this all-important unit and associated equations in the following tutorials.

## Are forces a scalar or vector measurement?

Because forces have both a direction and a magnitude, they are a vector measurement. This means that we can add and subtract them like any other vector measurement.

## Forces can be positive or negative

In the same way that acceleration can be positive and negative, so too can a force. Traditionally speaking, forces acting in the *northerly* or *easterly* direction are given a *positive* attribute, and forces acting in the *southerly* or *westerly* direction are given a *negative* attribute.

Attributing the correct the signs is particularly important for when we start adding and subtracting forces, but before we get into that, let's look at Newton's Three Laws of Motion.

## What are Newton's Three Laws of Motion?

Newton's Laws are simple and yet essential in understanding forces. They tell us what happens when you have balanced and unbalanced forces acting on an entity or system, and by doing so, they help explain what is going on in the world around us.

As the question heading above suggests, there are *three* laws, or statements, that Newton made about forces. Let's take a look at each of them separately, starting with the first one.