What happens to force of Friction when Force of Gravity is DOUBLED?

[ah sa]

would the force of gravity also double? and what about when the force of gravity triples, then what would happen to the force of friction? Would it be the same down the road, like for example, when it quadruaples, would the force of friction also quadruaples..and have a direct relationship btw. force of gravity and force of friction?

[russ_watters]

Friction force is the friction coefficient times the normal (perpendicular) force. So if you double the normal force (often resulting from gravity), you double the friction.