P2(i) - Forces and Motion 3.

Mass, Weight and Gravity.

Gravity is the Force of Attraction Between All Masses.

Gravity attracts all masses, but you only notice it when one of the masses is really big, e.g. a planet. Anything near a planet or star is attracted to it very strongly.

This has important effects:

1) On the surface of a planet, it makes all things accelerate towards the ground (all with the same acceleration, g, which is about 10m/s² on Earth).

2) It gives everything a weight.

3) It keeps planets, moons, and satellites in their orbits. The orbit is a balance between the forward motion of the object and the force of gravity pulling it inwards. 

Weight and Mass are Not the Same.

1) Mass is just the amount of "stuff" in an object. For any given object this will have…