What is the relation between a fixed force and work?

A force does work if there is atleast a component of the force in the direction of displacement of the block. The small work done $ dw $ by a constant force $ f $ in displacing the block through a small displacement $ ds $ is given by $ dw=fdscostheta $, where $theta$ is the angle between the force vector and the displacement vector. Since, power is work done per unit time,that is, $ p= frac{dw}{dt} $ .

That is, $ p= fvcostheta $, , where $theta$ is the angle between the force vector and the velocity vector.