Final answer:
A rock and a feather do not hit the ground at the same time due to air resistance, which significantly slows down the feather. The feather's weight is balanced by air resistance as it falls, while the rock is less affected and falls at a higher terminal velocity.
Step-by-step explanation:
When you drop a rock and a feather at the same time from the same height, they don't hit the ground at the same time because of air resistance. The feather experiences air resistance much more significantly than the rock does because of its shape and the relative area that is exposed to the air. This air resistance opposes the force of gravity and, as a result, causes the feather to fall more slowly than the rock. The speed of the feather increases more gradually than that of the rock due to the fluttering effect caused by air resistance and air movements.
As the feather falls, its weight is balanced by the force of air resistance. For the feather, this means that it will reach a terminal velocity where the air resistance equals its weight, preventing further acceleration. In contrast, the rock, with its larger mass and lesser surface area relative to the feather, will reach a much higher terminal velocity.