Question

an astronaut drops two pieces of paper from the door of a lunar landing module. one piece of paper is crumpled, and the other piece is folded into an airplane. why do the two pieces of paper land on the moons surface at the same time? (1 point)
the pieces of paper were not dropped from a sufficient height for air resistance to affect their falls.
the moon has practically no atmosphere, so there is no air resistance.
the mass of the paper folded into an airplane must be greater than the mass of the crumpled paper.
the moons gravity is much weaker than the earths.

Explanation:

On Earth, air resistance affects falling objects' speeds. But the Moon has almost no atmosphere. So, there's no air resistance to slow either piece of paper. They both accelerate at the same rate due to the Moon's gravity (\(g_{Moon}\)) and land at the same time.

• First option: Even if dropped from a height, on Earth air resistance would matter. But on Moon, no atmosphere (so no air resistance), not about height.
• Third option: Mass isn't the reason here. In a vacuum (Moon's case), \(F = mg\) and \(a=\frac{F}{m}=g\) (mass cancels out).
• Fourth option: Moon's gravity is weaker (\(g_{Moon}\approx\frac{1}{6}g_{Earth}\)), but that's not why they land at same time. It's lack of air resistance.

Answer:

The Moon has practically no atmosphere, so there is no air resistance.