$A$ mass of $10\, kg$ is at a point $A$ on a table. It is moved to a point $B$. If the line joining $A$ and $B$ is horizontal,what is the work done on the object by the gravitational force? Explain your answer.

(N/A) The work done by the gravitational force acting on the body is zero.
This is because the gravitational force acts vertically downward,while the displacement of the object is horizontal.
Since the angle $\theta$ between the force and the displacement is $90^\circ$,the work done $W$ is calculated as:
$W = F \cdot s \cdot \cos(90^\circ)$
Since $\cos(90^\circ) = 0$,the work done $W = 0$.