The crew of a cargo plane wishes to drop a crate of supplies on a target below. to hit the target, when should the crew drop the crate? ignore air resistance.
a) before the plane is directly over the target
b) when the plane is directly over the target
c) after the plane has flown over the target

a) Before the plane is directly over the target  

Explanation:

When a crate would be dropped from the cargo plane, its initial vertical velocity would be zero (free fall) but it would still have horizontal velocity of the moving plane. Therefore, the falling crate would transverse a parabolic path.

In order to make it hit the target, the crate should be dropped before the plane is directly over the target because of the horizontal component of net velocity will take the crate towards the target.

Thus, option a is correct.