A man throws a ball vertically upwards from a point 4 m above horizontal ground with speed 8 m s-1. The motion of the ball is modelled as that of a particle moving freely under gravity. 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 hit the ground. Give your answer correct to 3 significant figures.