A plastic ball weighing m = 10 g. It falls on a horizontal plane from a height h1 = 25 cm and after the impact rises to a height h2 = 9 cm. Find the average impact force if the contact of the ball with the plane lasted t = 0.04 s.

A detailed solution with a brief note of the conditions, formulas and laws used in the solution, the derivation of the calculation formula and the answer.