Hi. I have this question hat I'm not sure on.

Alison has let her hamster run loose in her living room. The position function of the hamster is $\displaystyle s(t)=\frac{5t}{t^2+4}$, t is greater than or equal to 0, where s is in metres, and t is in seconds.

A) how fat is the hamster moving after one second.

I think I get this one, since the original function is a speed function and speed is a change in position then the derivative would yield the position after 1 s.

B) when does the hamster change direction?

I'm not sure how would I tell when the hamster changes direction.