How long will it take a shell fired from a cliff at an initial velocity of 800 m/s at an angle 30 degrees above the horizontal to reach the ground 150 meters below?

Answer 1

The equation you have to solve is

80 sin 30 t - (g/2) t^2 = -150

which can be rewritten

40 t - 4.9 t^2 = -150

Answer 2

0.37