A particle moves along a line according to the law `s(t)=2t^(3)-9t^(2)+12t-4`, where `t ge 0`.
(i) At what times the particle changes direction ?
(ii) Find the total distance travelled by the particle in the first 4 seconds
(iii) Find the particle's acceleration each time the velocity is zero.

Answer

`(i) 1,2` sec `(ii) 34m` `(iii)-6m//s^(2)`, `6m//s^(2)`