Question

A ball is dropped from a certain height, and at that exact same moment a rock is fired horizontally from the exact same height above ground level.
Assuming that air resistance is negligible, which object will strike the ground first?

• A. The ball will hit first
• B. The rock will hit first
• C. They will hit at the same time
• D. The answer to this question depends on precisely how fast the rock is fired

Answer 1

The correct option is C They will hit at the same time

The time of projectile hitting the ground is found by

$h=u_{y}t+\frac{1}{2}g{t}^2$

Since $u_y$ in both the cases is zero, the time of hit at ground is $\sqrt{\frac{2h}{g}}$ which is same for both the projectiles.