Question

A rock is thrown from the edge of a cliff with a horizontal velocity component vx. The rock travels a horizontaldistance x before it strikes the ground. In order for the rock to travel a horizontal distance 2x, what must be the initial horizontal velocity of the rock in terms of vx?

Answer 1

The horizontal motion of the rock is a rectilinear motion. Then it is described as:

$v=\frac{d}{t}$

If we want the distance to be 2x in the same time then the velocity will have to be:

$\begin{gathered} v_x=\frac{2x}{t} \\ \frac{v_x}{2}=\frac{x}{t}_{} \end{gathered}$

Therefore the velocity will have to be:

$\frac{v_x}{2}$

and the answer is a.