Question

The displacement of a particle, starting from rest (at $t=0$ ) is given by
$s=6 t^{2}-t^{3}$
The time in seconds at which the particle will attain zero velocity again is

• A. 2
• B. 4
• C. 6
• D. 8

Answer 1

Answer: (B)

Given $ s=6 t^{2}-t^{3}$
Velocity $v=\frac{d s}{d t}=12 t-3 t^{2}$
If velocity is zero, then
$0 =12 t-3 t^{2} $
$\Rightarrow t =4 s$