You accidentally throw your car keys horizontally at 10.0 m/s from a cliff 54 m high. How far from the base of the cliff should you look for the keys?

Answer 1

some accident ...

you need the flight time
... zero is on the ground, 54 is starting height
... remember gravitational acceleration is downward

0 = 1/2 g t^2 + 54 ... 0 = -4.9 t^2 + 54

solve for t (flight time)
... multiply by 10 m/s to find the distance