Answer:
Below in bold.
Explanation:
(A). s = (1/3)t^3 - 3t^2 + 9t + 7
To find the velocity at time t we find the derivative:
V = ds/dt = 3*1/3 t^2 - 3*2t + 9
V = t^2 - 6t + 9,
Acceleration is found by finding the derivative of the velocity:
A = 2t - 6.
(B). Acceleration after 1 second = 2(1) - 8
= -6 ms^-2.
(C). When V = 0
acceleration = 0 ms^-1.