If you can throw a stone straight up to a height of 18m, how far could you throw it horizontally over level ground? Assume the same throwing speed and optimum launch angle.

Answer 1

fall from 18 m, what is speed
(1/2) m v^2 = m g h
vlaunch = sqrt(2 gh)
that is your launch speed for second part

optimum launch angle is 45 degrees. so do horizontal and vertical problems
u = horizontal velocity = vlaunch/sqrt 2
Vi = initial speed up = vlaunch/sqrt2
distance = u * t
find t from vertical problem, up and down