When Dave Scott dropped a hammer and a feather on the Moon during the Apollo 15 mission, both objects fell at the same rate and hit the lunar surface simultaneously. This phenomenon occurs because, in the absence of an atmosphere, there is no air resistance to affect the motion of objects.
On Earth, a feather falls slowly compared to a hammer due to air resistance acting on the feather, which is light and has a larger surface area relative to its weight. However, on the Moon, where there is almost no atmosphere, both the hammer and the feather are subject to the same gravitational pull, allowing them to fall freely without any opposing forces.
This experiment demonstrated Galileo's principle that in a vacuum, all objects fall at the same rate regardless of their mass. Scott's demonstration was a powerful illustration of fundamental physics and helped to reinforce our understanding of gravity and motion.