physics

Gravitational force is the force of attraction between all masses...

Gravity attracts all masses, but you only notice it when one of the masses is really really big, e.g a planet. Anything near a planet or star is attracted to it very strongly. This has 2 important effects:

1) On the surface of a planet, it makes all things accelerate towards the ground.

2) It gives everything a weight

Weight and mass are not the same...

Mass is just the amount of stuff in an object. For any given object this will have the same value anywhere in the universe. Weight is caused by the pull of the gravitational force. In most questions the weight of an object is just the force of gravity pulling it towards the centre of the earth. An object has the same mass whether it's on earth or on the moon- but its weight will be different. A 1kg mass will weigh less on the moon(about 1.6N) than it does on earth (about 10N), simply because the gravitational force pulling on it is less. Weight is a…