The work done on an object does not depend upon the

The work done by a force on a body will be positive if the:

What is the work done by a coolie walking on a horizontal platform with a load on his head?

$(a)$ State the law of conservation of energy.
$(b)$ Establish the relation between the $SI$ unit of energy and the commercial unit of energy.
$(c)$ $A$ toy car is displaced through $5 \, m$ on the application of a force of $7 \, N$. Assuming the force acts on the object throughout the displacement,what is the work done in this case?

$A$ man weighing $50 \, kg$ lifts a weight of $30 \, kg$ to the top of a building $10 \, m$ high. Find the work done by him. (Take $g = 9.8 \, m s^{-2}$) (in $, J$)

$A$ box of mass $10 \, kg$ is placed at point $A$ on a horizontal surface. It is moved to point $B$,which is at a distance of $2 \, m$ from $A$. If the line joining $A$ and $B$ is horizontal,find the work done by the gravitational force on the box. Justify your answer. $(g = 10 \, m s^{-2})$ (in $, J$)