Question

A coolie is walking on a horizontal platform with a load placed on his head. The mass of load is $5\text{kg}$. If the coolie travels a distance of $10\text{m}$, the workdone by him on the load is :

• A. $500\text{J}$
• B. $500\text{J}$
• C. zero
• D. $1000\text{J}$

Answer 1

The correct option is C zero

If we focus on the load placed on coolie's head, we see that coolie is pushing the load in vertically upward direction from the point of contact of his head.
Since, the force apllied on load is in perpendicular direction to the displacement of load, thus $W_F=0$
$W=F\times d$
(Here we take ${}^{\prime }{d}^{\prime }$ as the displacement in the direction of force ${}^{\prime }{F}^{\prime }$)