An object of mass $40 \text{ kg}$ is pulled up to a height of $0.5 \text{ m}$. Calculate the work done. (Given $g = 9.8 \text{ m s}^{-2}$) (in $J$)

How is work done by a force measured? $A$ porter lifts a luggage of $20 \, kg$ from the ground and puts it on his head $1.7 \, m$ above the ground. Find the work done by the porter on the luggage. $(g = 10 \, m s^{-2})$

List two conditions which need to be satisfied for the work to be done on an object.

Four persons jointly lift a $250 \,kg$ box to a height of $1 \,m$ and hold it.
$(a)$ Calculate the work done by the persons in lifting the box.
$(b)$ How much work do they do just holding it?
$(c)$ Why do they get tired while holding it? $(g = 10 \,m/s^2)$

What is the work done by the tension in the string of a simple pendulum?

Write an expression for the work done when a force is acting on an object in the direction of its displacement.