Question

a student drops a ball from a window while a second student throws an identical ball horizontally from the same window at the same time. which ball hits the ground first (ignoring air resistance)? the ball that was dropped. the ball with the greater mass. they both hit the ground at the same time. the ball that was thrown horizontally.

Explanation:

The vertical motion of both balls is a free - fall motion. The initial vertical velocity of both balls is 0 (the dropped ball has no initial velocity and the horizontally - thrown ball has only an initial horizontal velocity). Using the equation of motion for vertical displacement $y = v_{0y}t+\frac{1}{2}gt^{2}$, with $v_{0y} = 0$ and $y$ (height of the window) being the same for both, the time $t=\sqrt{\frac{2y}{g}}$ is the same for both balls.

Answer:

C. They both hit the ground at the same time.