Question

Does friction depend on gravity?
If the gravitational force would be twice as strong here on Earth, would it be twice as hard to move objects in a horizontal plane?

Answer 1

Think about it like this.
Fg(Force of Gravity)=mg (mass*acceleration due to gravity)
Fn(normal force)=Fg
When Fg increases, Fn increases directly proportionally.
Then, you have the equation Ff(Force of Friction)=uFn (friction coefficient constant * normal force)
If you make up an object with a mass of 1kg and put it in a scenario with 1m/s^2 of acceleration due to gravity and compare it to a place with 2m/s^2 (gravitational force 2x as strong), you'll find your answer.