**Gravitation 1.4**

**1.4.1 Gravitation**

We know from Higher that Newton's Law of Universal Gravitation relates the gravitational force (F) between two masses to their separation in space and to the Gravitational Constant (G):

^{-11}Nm

^{2}kg

^{-2})

M is the mass of the larger body (e.g. planet)

m is the mass of the smaller body (e.g. moon)

r is the radius (distance) between the centres of mass.

The following simulation should help you to visualise this effect:

**1.4.2 Gravitational Fields**

A gravitational filed is a region, around a massive body, where a gravitational force is experienced. ** Gravitational field strength** at any point is defined as the force per unit mass at that point (Nkg

^{-1}). As Newton's Law implies: