Physics 3 - Turning Forces - Gravitational Attraction

The earth exerts a force of gravity on us all.

In fact, any two objects exert a force of gravitational attraction on each other. The force depends on the mass of each object.

The earth is a massive object so its force of gravitational attraction on each of us keeps up on the ground.

Newtons Rules on Gravity:

Sir Isaac Newton devised the theory of gravity over 300 years ago. He used his theory to explain why the planets orbit the Sun and why the Moon orbits the Earth. He said that the force of gravity between two objects:

- Is and attractive force

- Is bigger the greater the mass of each object is

- Is smaller the greater the distance between the two objects

The gravitational field strength of the Earth at its surface is 10 Newtons per Kilogram (N/kg).

So the force of gravity on a 50kg person on Earth is 500 N.

The gravitational field strength of the Moon at its surface is 1.6 N/kg. So the force of gravity on a 50kg person on the moon would be 80 N.