I have seen youtube videos where two balls of the same size and of different masses are dropped from the same height and they hit the ground at the same time. I understand why this is so: the increase in the mass of a body increases the force of gravity acting on the body, but also decreases the body's willingess to move. It makes sense to me in vacumm, but it somehow collides with what i have found written in my textbook. It goes more less like this: If you dropped an ant from a certain height in the air, it would not die upon landing, because the increase in speed as it is falling entails the increase of air resistance acting on the ant. The force of air resistance quickly balances the force of gravity acting on the ant. Up to this point the ant hasn't gained much speed and now is no longer accelerating. The speed is too little to cause it much harm when landing. Then it says that if you dropped a human from that height it would also stop accelerating at some point (at the point of air resistance balancing the body's weight), but it would happen much later. Therefore a human would gain more speed before landing and would die. This brings me back to the experiment with two balls. Why doesn't the same principle work here? I know their shape makes air resistance less powerful but it must still be there. The lighter ball has lesser weight, so it should take less time for air resistance to counter the ball's weight than it should take in the case of the ball with greater mass. The heavier ball should accelerate longer then the lighter ball, and therefore it should hit the ground first. Please tell me, where is the error in my thinking.