A particle moves along a straight line such that its displacement s at any time t is given by `s=t^3-6t^2+3t+4m`, t being is seconds. Find the velocity of the particle when the acceleration is zero.

Options

A. `3 m//s`
B. `-12 m//s`
C. `42 m//s`
D. `-9 m//s`

Answer

D

Explanation

`s=t^(3)-6t^(2)+3t+4`
`v=(ds)/(dt)=3t^(2)-12t+3`
`a=(dv)/(dt)=6t-12`
When `a=6t-12=0impliest=2 s`
At `t=2 s, v=3(2)^(2)-12(2)+3`
`=-9 m//s`