After t seconds, a particle has covered a distance of S meters, where S=t^3-3t^2+9t+1

Question

Determined the time when:
(i) Velocity is zero
(ii)Acceleration is zero
(b)Find its velocity and acceleration when t=2 seconds.
(c) What is the acceleration after 6 second s?

Answer 1

S=t^3-3t^2+9t+1
then the velocity is
v = ds/dt = 3 t^2 - 6 t + 9
solve that quadratic for v = 0
then
a = dv/dt = 6 t - 6
obviously a = 0 when t = 1

I think you can put t = 2 in the v equation and t = 6 in the a equation

Answer 2

Pls show how to get t when V is zero