Originally Posted by

**live_laugh_luv27** Particle moves along vertical axis, position at any time t greater than or equal to 0 is given by the function $\displaystyle s(t) = \frac{1}{3}t^3-3t^2+8t-4$,$\displaystyle s$ is centimenters and $\displaystyle t$ is seconds.

a. Find the displacement during the first 6 seconds

b. Find the average velocity during the first 6 seconds

c. Find expressions for velocity and acceleration at time $\displaystyle t$

d. For what values of $\displaystyle t $ is the particle moving downward?

Here are my answers...are they correct? thanks.

a. 12 ok

b. -10 no ... avg v = displacement/time

c. $\displaystyle v(t) = t^2-6t+8$ ok

$\displaystyle

a(t)=2t-6

$ ok

d. $\displaystyle t$ is less than 0? I'm not sure how to do this one..

find the interval where v(t) < 0