Here's why:
* Air resistance: In the presence of air, the feather experiences much more air resistance than the hammer due to its larger surface area and lighter weight. This causes the feather to fall much slower.
* Vacuum eliminates air resistance: In a vacuum, there is no air to resist the fall of either object. This means that both the hammer and the feather experience only the force of gravity, which acts equally on all objects regardless of their mass.
The famous demonstration: This principle was famously demonstrated by Apollo 15 astronaut David Scott on the surface of the moon. Because the moon has practically no atmosphere, both the hammer and the feather dropped simultaneously and landed at the same time.
So, while you can't recreate this experiment on Earth's surface without a vacuum chamber, it's a fundamental principle of physics: In the absence of air resistance, all objects fall at the same rate regardless of their mass.
