Question

You accidentally throw your car keys horizontally at 8.0 m/s from a cliff 54 m high. How far from the base of the cliff should you look for the keys?

Answer 1

Strategy:
1) Find the time for the key to reach the ground.
2) Find horizontal distance covered in that time.

Answer 2

\[R=u \sqrt{\frac{ 2H }{ g }}\]

Answer 3

Following on from Imron07's good advice, I would substitute 54 into the equation height=0.5gt2 where g is the gravitational constant of 9.8ms-2 and t is the time for the fall. From that multiply the time by the horizontal speed and assume the keys don't slow down very much because of air resistance. I have an answer if you want to check yours.