Answer:
Below in bold.
Step-by-step explanation:
a. h after 4 seconds:
h = -16(4)^2 + 256(4)
= -256 + 1024
= 768 ft
b. When the height is 1008 ft
1008 = -16t^2 + 256t
16t^2 - 256t + 1008 = 0
16(t^2 - 16t + 63) = 0
16(t - 7)(t - 9) = 0
t = 7, 9
So it will take 7 seconds to rise to 1008 feet and and after 9 seconds it will pass 1008 on the way down
So the times are 7, 9 seconds.
c. When the ball reaches the ground h = 0:
-16t^2 + 256t = 0
-16t(t - 16) = 0
t - 16 = 0
t = 16 seconds.
