Answer:
7 seconds
Step-by-step explanation:
Given the height equation of the motion;
s = -16t^2 + 256t
At s = 1008 ft
The equation becomes;
1008 = -16t^2 + 256t
16t^2 - 256t + 1008 = 0
Solving the quadratic equation for t;
Factorising, we have;
16(t-7)(t-9) = 0
t = 7 or t = 9
When the ball is going up it would reach the given height at time t = 7 seconds.
When it is coming down it would reach the given height at time t = 9 seconds.
