However, the premise of this definition is that the directions of F and S are unchanged in the process of doing work, and the magnitude is the product of the lengths of two vectors, which can be the adsorption force produced by some chemical actions. As the definition of work has already said, s is the displacement vector. F is the vector of force, and F and S can be regarded as invariable (invariable in the limit sense), so it is necessary to divide the process of doing work into several wireless and extremely short meta-processes, such as magnetic field force, in order to be more universal.

The definition of work in college physics is essentially W=F*S (inner product).