A hammer and a feather are dropped from the same height with no air resistance. Which value will be different for the two objects? A) the upward push of air resistance B) the velocity of the objects C) the gravitational attraction between the Earth and the objects D) the time it takes for them to fall

What “no air resistance” changes in a drop

If air resistance is zero, the only significant force acting on each falling object is gravity. That means both objects are in free fall.

Comparing the choices using free-fall facts

• A) Upward push of air resistance: With no air resistance, this force is $0$ for both, so it is not different.
• B) Velocity of the objects: In free fall, both have the same acceleration $g$, so starting from rest they have $$v = gt$$ at the same time $t$, so their velocities match.
• D) Time it takes for them to fall: From height $h$ (starting from rest), $$h = \tfrac{1}{2}gt^2 \quad \Rightarrow \quad t = \sqrt{\tfrac{2h}{g}}$$ which does not depend on mass, so the time is the same.

Why choice C is the one that differs

The gravitational force (weight) depends on mass: $$F_g = mg.$$ Since the hammer has a larger mass than the feather, the hammer has a larger gravitational attraction with Earth. So C is different.