# What is Newton's constant G?

##### 1 Answer

G is the gravitational constant.

#### Explanation:

The universal law of gravitation says that the force of attraction between 2 bodies is *proportional to* the product of their masses,

So to get the the force of attraction

G has both a number as part of it and a combination of units. The constant G to make the formula come out in Newtons is:

The units that are part of that constant are necessary to allow the units from the 2 masses and the square of the radius to be cancelled leaving Newtons as the only units on the result.

It is similar to the weight of a mass here on Earth. The weight is proportional to the mass. But, to get the weight in Newtons, you have to multiply by a constant of proportionality, which in that case is the acceleration due to gravity at the Earth's surface

The acceleration due to gravity at the Earth's surface is given by:

Where

I hope this helps,

Steve