A ball of mass m with initial velocity u rebounds from a wall, with final velocity v. Using Newton's laws of motion explain forces acting in the system.
The ball has initial momentum p1= mu, and final momentum p2=vm. According to the Newton's 2nd law of motion a force exerted on the ball is equal to the rate of change of momentum . It is thus:F = ( p2-p1)/t , where t is the time of interaction (instert suitable diagram). Substituting for momenta:F = (mv - mu)/t, or F = m(v - u)/tTherefore knowing the magnitude of velocities, it is possible to calculate the force exerted on the ball by the wall during the collision. Note that velocities are vectors, so u and v are of opposite signs.According to the Newton's 3rd law of motion, if object A exerts some force on object B, then object B exerts force of the same magnitude but opposite direction on object A.In the presented case this means that the ball acts on the wall with a force of the same magnitude but opposite direction (instert suitable diagram).
