Position/acceleration derivatives problem

[NATURE.M]

Homework Statement

An object is traveling along a linear path according to the equation s(t) = 4t^3 - 3t^2 + 5 where t is measured in seconds and s(t) measured in meters. How far has the object traveled when its acceleration is zero?

Homework Equations

The Attempt at a Solution

The acceleration time function is (or second derivative of position) is, a(t)= 24t-6.
Then since a(t)=0, t=1/4 s.
And know we take the difference between s(1/4) and s(0), since the object initially starts 5m to the right of the origin at t=0s.
So, d=s(1/4)-s(0)
=-1/8m
Is this correct?

 

[HallsofIvy]

Yes, that is well done.