Question

if you dropped a penny, a tennis ball, and a feather from the same height in a vacuum (no air), which object would hit the bottom first?
penny
tenis ball
feather
they would all hit at the same time

Explanation:

In a vacuum, there is no air - resistance. All objects fall with the same acceleration due to gravity ($g$). Using the kinematic equation $h = v_0t+\frac{1}{2}gt^2$ (where $v_0 = 0$ as they are dropped), the time $t$ it takes to fall a height $h$ only depends on $h$ and $g$. Since $h$ and $g$ are the same for all three objects, they will take the same time to reach the bottom.

Answer:

they would all hit at the same time