1. The problem statement, all variables and given/known data When a ball is bounced from the ground, the earth exerts the force necessary to reverse its velocity. Is there a simultaneous force exerted on the earth? If there is one, why don't we perceive any acceleration of the earth? 2. Relevant equations Newton's second law: net F=ma, F and a being vectors Newton's third law: all forces act in pairs, equal and opposite 3. The attempt at a solution So when the ball is say released from my hand it heads toward the ground. Now the ball's velocity is changing and therefore is accelerating. Its speed is increasing but its direction is in the downward direction. Now the acceleration of the ball is due to the force of attraction of earth. That makes sense to me. However, when the ball hits the ground, its exerts a force on the ground (normal force') and the ground exerts an upward force (normal force). The ball has another force acting on it, its weight and it exerts a force (weight') on the earth. But I'm confused which force causes the ball to bounce back in the opposite direction, causing it to accelerate it upwards. I know that the earth does accelerate but its effect is trivial since mass of earth is large relative to the ball.