A particle moves along a straight line OX. At a time (in second) the distance x (in metre) of the particle from "O' is given by : `x=40+12t-t^(3)` How long particle travels before coming to rest ?

Options

A. 16 m
B. 21 m
C. 40 m
D. 56 m

Answer

d

Explanation

Here `x=40+12t-t^(3)`
`v=(dx)/(dt)=12-3t^(2)`
For `v=0,3t^(2)`=12 or `t=2s`
`:.x=40+12xx2-(2)^(3)`
64-8=56 m.