Dynamics Question on projectile motion

[leonsilavant]

Homework Statement

A stone of 0.5kg is thrown horizontally from an edge of a cliff at 6 m/s. If the cliff is 20m, what is the horizontal distance traveled by the stone before landing?

Homework Equations

I am guessing the equations are the standard SUVAT ones and possibly F=ma:

v^2 = u^2+2as
s = (ut) + 1/2(u[t^2])
v = u + at

The Attempt at a Solution

I have no solution so far because i have totally forgotten how to do it. Its for a engineering principles retake exam.

Please help!

 

[SteamKing]

Neglecting air resistance, the horizontal velocity of the rock will remain unchanged while the rock falls to the ground at the bottom of the cliff. What you must do first is calculate how long the rock takes to fall, as if it were dropped directly from the top of the cliff. Once you have the time to fall, you can calculate how far the rock travels horizontally using the velocity and duration of the fall.