A hill is ` 500 m` high. Supplies are to be across the hill using a canon that can hurl packets at a speed of `125 m//s` over the hill . The canon is located at a distance of ` 800 m` from the foot to hill and can be viewed on the ground at a speed of 2 m//s , so that its distance from the hill can be adjusted. What is the shortest time ( in second ) in which a packet can reach on the ground across the hill ? ` g= 10 m//s^2`.

Answer

45