i think the given function is wrong because when you substitute any value of t, the h will always increase. the correct function, it must reach zero, it the time it reach the water. the function should be h = 16t^2 - 40
so the time the orange hit the water is when h = 40, then solve for t
40 = 16t^2 - 40
80 = 16t^2
t^2 = 80/16
t = 2.24 seconds