Work, Energy and Power

In this post we will discuss about the importance of the topic work, energy and power in JEE advanced and JEE mains. Also we will focus on the types of questions that generally come from this section.

But before we do that we shall have a look at the past year trends -

Importance of this topic can be understood by the fact that any problem of mechanics can be solved by using energy approach. Many questions can be easily solved by using concepts of work, energy and power, specially when force approach seems tedious. As you can see from the past year trends that direct questions from this topic have increased and you can expect about 2-4 questions in both the exam papers.

This is one of the very few topics whose scope is very wide and it can be mixed with other topics to form some very tricky questions which can be solved very easily if you are comfortable with this topic.
Now let us see some important areas of this topic which require special attention.


Start this topic by understanding concept of work done by different kinds of forces. Before solving a problem always check if you are dealing with conservative or non conservative forces.

Once you know the nature of force see if you can apply law conservation of energy of energy(which is possible if you can account for every work and gain/loss of energy).
Mostly questions require you to apply work energy theorem which states that kinetic energy of any body changes by virtue of work done by the net force on the body.

For conservative forces like gravitation, spring force, etc. you must know the concept of potential energy and how it changes when force acts on the given body, eg. in closed path change in potential energy is zero and so on. Usually, questions of this kind require you to balance potential energy, kinetic energy and work done.

To deal with questions that require you to calculate power, always remember that it is rate of work done or rate of change of energy and use this differential relationship to find power easily.

Also, I would recommend you to derive relations between different kinds of energy related to common conservative forces(eg. gravitation, electrostatic force, spring force, etc.) to give you a clear understanding of this topic.

Those were the parts which are important and you should pay attention to them while solving questions. Finally, practice more and more questions at eagerbug to get more confident and attain higher accuracy and speed.

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