In each of the following cases,a force $F$ is acting on an object of mass $m$. The direction of displacement is from west to east,shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative $(-ve)$,positive $(+ve)$,or zero $(0)$.

(N/A) Case $I$: The force $F$ is acting in the vertically upward direction,while the displacement of the object is in the horizontal direction (from west to east). Since the force and displacement are perpendicular to each other (angle $\theta = 90^\circ$),the work done is $W = F \cdot s \cdot \cos(90^\circ) = 0$.
Case $II$: Here,the force $F$ is applied in the same direction as the displacement. Since the angle between force and displacement is $0^\circ$,the work done is positive $(+ve)$,as $W = F \cdot s \cdot \cos(0^\circ) = F \cdot s$.