How much energy could you produce with magnets in perpetual motion

Acricket ball of 70g moving with a velocity of 0.5 m/s is stopped by a player in 0.5s what is the force applied to stop the ball

Acup of coffee sits on the dashboard of an automobile. the car goes around a sharp curve. even though you hold the cup still, coffee still splashes out. this can best be explained due to a) density. b) friction. c) gravity. d) inertia.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?