$A$ lamp consumes $1000\, J$ of electrical energy in $10\, s$. What is its power (in $, W$)?

An object of mass $40\, kg$ is raised to a height of $5\, m$ above the ground. What is its potential energy? If the object is allowed to fall,find its kinetic energy when it is half-way down.

$A$ pair of bullocks exerts a force of $140 \, N$ on a plough. The field being ploughed is $15 \, m$ long. How much work is done in ploughing the length of the field (in $, J$)?

The kinetic energy of an object of mass,$m$ moving with a velocity of $5 \,m \,s^{-1}$ is $25\, J$. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?

What is the work done by the force of gravity on a satellite moving around the Earth? Justify your answer.

When do we say that work is done?