The distance moved by the particle in time t is given b

The distance moved by the particle in time t is given b
|

The distance moved by the particle in time t is given by x=t312t2+6t+8. At the instant when its acceleration is zero, then the velocity is

A.

42

B.

-42

C.

48

D.

-48

Please scroll down to see the correct answer and solution guide.

Right Answer is: B

SOLUTION

We have,
x=t312t2+6t+8
dxdt=3t224t+6andd2xdt2=6t24
Now, Acceleration =0
d2xdt2=06t24=0t=4
Att=4, we have
Velocity =(dxdt)r4=3×4224×4+6=42.

Hence (b) is the correct answer.