In the figure the top view of a compartment of a train is shown. A man is sitting at a corner `'B'` of the compartment . The man throws a ball `(` with respect to himself `)` along the surface of the floor towards the corner `'D'` of the compartment of the train. The ball hits the corner `'A'` of the compartment, then find the time at which it hits `A` after the ball is thrown . Assume no other collision during motion and floor is smooth. The length of the compartment is given `'l'` and the train is moving with constant acceleration `'a'` in the direction shown in the figure.