Question

Centrifugal force increases with _______________.

Answer 1

I would say angular speed.

Centrifugal force is a fictitious force (acting away from the axis of rotation) that "balances" centripetal force (acting towards the axis of rotation) to ensure the object moving in a circle does not accelerate off its circular path and so the centrifugal force has the same magnitude but opposite direction of the centripetal force. The magnitude of centripetal force (|F|) is related to angular speed by |F| = mr|ω|^2, where m is the mass of the object, r is the radius of curvature, and |ω| is the angular speed.

You can see centripetal force increases with the square of angular speed, and so centrifugal force must increase at the same rate to balance it.