A hammer and a feather are dropped from the same height by an astronaut on a planet without air. how will their falls compare?
On a planet without air, such as the Moon or any airless environment, both the hammer and the feather will fall at the same rate and hit the ground simultaneously. This is due to the absence of air resistance, which is the force that opposes the motion of objects through the air.
On Earth, because of the presence of air resistance, the feather experiences a significant air resistance force while falling through the atmosphere, causing it to fall much slower than the hammer. However, in the absence of air on the airless planet, there is no air resistance acting on either object, allowing both the hammer and the feather to fall at the same acceleration and speed.