第一个问已经做出来,求第二问最好带过程,
If a ball is thrown vertically upward from the roof of a 32 foot tall building with a velocity of 112 ft/sec,its height in feet after t seconds is s(t) = 32 + 112 t - 16 t^2.What is the maximum height the ball reaches?（228）
What is the velocity of the ball when it hits the ground (height 0)求第二问过程