projectile is launched horizontally from edge of cliff 20 m high with an initial speed of 10 m/s. what is the horizontal distance the projectile travels before striking the level ground below the cliff?

Question

what formula do i use?

Answer 1

First the vertical problem:
How long to fall 20m?
0 = 20 + 0 t -(1/2)9.8 t^2
4.9 t^2 = 20
t = 2.02 seconds in the air
Now the horizontal problem:
How far in 2.02 seconds at 10 m/s?
20.2 meters
The end.

Answer 2

thanks!