Following text: "Galileo Galilei is supposedly the first one to prove that the speed of a falling object is independent of its mass. He did this by demonstrating that a 100 pound cannonball and a one pound ball dropped at the same time from the Leaning Tower of Pisa reached the ground at the same time. The acceleration of gravity is therefore independent of mass." I have never really understood why it hits the floor at the same time. When I look at the formula F = mg, I would say the force of gravity is greater for the 100 pound ball, so why does it not fall faster? Let's also assume that it's performed in vacuum.