What way is more effective when trying to make magnets repel further/faster, using strong magnets over weak magnets or putting the magnets closer together?

Avery hard rubber ball (m = 0.5 kg) is falling vertically at 4 m/s just before it bounces on the floor. the ball rebounds back at essentially the same speed. if the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?

On average 8 bananas make up one pound. the price is four pounds for 5.00. you must buy 25 bananas. what is your cost?

Determine the moment of the force f about an axis extending between a and c. express the result as a cartesian vector. a is at the origin, c is at (4,3,0) and f = (4i + 12j -3k) lb coming out of b (4,3,-2).