The rate at which the vector force is acting

Question

If $r$ is a position vector of a particle $P$ of mass $0.4$ kg at time $t$, where $r = t^3i + t^2 j + t^4k$,
how do I find the rate at which the force acting on $P$ is working at time $t$?

I worked out its velocity, acceleration and KE at $t$. But the rate is Power? If it is Power, it should be Force $\times$ Velocity and I don't know the force in this question.

Answer 1

Hint: It's simply asking $F.v$ To get that, all you need to do is $F=ma$ and scalar multiply with $v$. Mass will be constant