Question

I have studied that power= force × velocity

But how can a body applied by a force will have a constant velocity? Shouldn't it accelerate? Why is this violating the basic newtons laws

Answer 1

It is calculated instantaneously, for a particular moment. Off course under the effect of force, the body will accelerate and velocity will change.
P = F x V ; will give us the instantaneous power produced or used at that particular moment.