A ball is thrown vertically upwards from the top of a 96-foot tower with an initial velocity of 48 feet per second. Use the function s(t) = -16t 2 +v 0 t + s 0 where v 0 is the initial velocity and s 0 the initial height. (a) After how many seconds does the ball attain its maximum height? (b) What is the maximum height the ball attains? (c) After how many seconds does the ball return to the ground?