If a ball is thrown vertically upward from the roof of 48 foot building with a velocity of 96 ft/sec, its height after t seconds is s(t)=48+96t�16t^2. a.) What is the maximum height the ball reaches? I got the right answer for this, it is 192. I got this answer by taking the derivative of the original equation, setting it equal to 0, then plugging in the t value calculated back into the original equation. But my real question (if it has something to do with part a I saved you a little time) is the question below. b.) What is the velocity of the ball when it hits the ground (height 0)?