A mass of $10kg$ 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.

Hint: Observe the angle between force of gravity and displacement.

Explanation:

Step 1: Concept used:
Work done is given by:

$W=\overrightarrow{F}.\overrightarrow{S}$
$W=FS\cos \theta$

where, $F=$ force applied

$S=$ displacement

$\theta =$ angle between the force applied and displacement.

Step 2: Finding the work done:

In the given problem, the force of gravity and displacement are perpendicular to each other. 

$\theta =$ $90$
$\therefore W=0$ 

Hence, the work done is zero.