1) A 1.9-kilogram mud ball drops from rest at a height of 18 m. If the impact between the ball and the ground lasts 0.56s, what is the average force exerted by the ball on the ground?
2) A 4.90-kg ball, moving to the right (positive direction) at a velocity of +2.30 m/s on a frictionless table, collides head-on with a stationary 7.90-kg ball. Find the final velocity of the 4.90-kg ball if the collision is elastic.