A man stands on a ledge and throws a ball into the air so that, at the instant when the ball leaves his hand, the ball is 4 m above the ground and is moving vertically upwards with speed 8 ms-1. The motion of the ball is modelled as that of a particle moving freely under gravity and the acceleration due to gravity is modelled as being of constant magnitude 10 ms-2. The ball hits the ground T T\,T seconds after leaving the man's hand.
Using the model, find the value of TTT.