Horizontal Throws

A cannonball is fired horizontally at 15ms^-1 from a cliff that is 21m high. Calculate the time taken to hit the ground and the speed at which the cannonball hits the ground and the horizontal range.Vertically, u=0. So the ball effectively drops vertically and we can use s = ½at².so t = 2.07sFor the vertical velocity at which it hits the ground use v² = 2as therefore v = 20.3ms^-1. Combining this with the 15ms^-1 horizontal velocity by Pythagoras, the speed at which it hits the ground is √(15² + 20.3²) = 25.2ms^-1. The horizontal range is given by s = ut. The time of flight is 2.07seconds and u=15ms^-1. The horizontal range is 31.0m.