Here's why:
* Gravity: The force of gravity acts equally on all objects, regardless of their mass or shape. In a vacuum, there is no air resistance to slow the feather down.
* Air Resistance: In normal conditions, air resistance significantly affects the feather, slowing its descent and making it appear to fall much slower than the steel ball.
* Vacuum: In a vacuum, there is no air. This eliminates the air resistance that normally slows the feather down, allowing it to fall at the same rate as the steel ball.
This was famously demonstrated by Apollo 15 astronaut David Scott on the moon. In the near-vacuum environment of the moon, he dropped a feather and a hammer simultaneously, and they landed together.
