Consider a massive 500 kg boulder and a 1.0 kg rock. If both are dropped from the same height at the same time, which will hit the ground first? (Assume there is no air resistance)

Answer 1

It might defy your common sense but this is was Galileo's Leaning Tower of Pisa experiment. All objects, regardless of their mass, accelerate downward at the same rate (called the acceleration due to gravity or "g") and their mass has no effect on this. So, assuming air resistance is negligible, both will hit the ground at the same time.