A ball is projected vertically upwards at 10 m s-1 from the top of a vertical cliff 20 m above the sea. Model the ball as a particle moving freely under gravity and use g=9.8 m s−2g=9.8\text{ m s}^{-2}g=9.8 m s−2.
Determine the time taken for the ball to reach the sea.
Determine the speed with which the ball reaches the sea.