JEE Main Physics Work Energy and Power Handwritten Notes

JEE Main Work Energy and Power Handwritten Notes, free to download as a 20-page PDF. The topic is worth about 4 to 8 marks and takes roughly one day to learn, so treat it as a single focused sitting.

The notes are scans of a real notebook, so they read the way a topper's own pages do: short lines, boxed formulas, and a margin note where something is easy to get wrong.

JEE Main Work Energy and Power Weightage

Physics is 25 of the 75 questions in JEE Main, each worth four marks with one deducted for a wrong answer. Unit 4 usually contributes one or two of them.

What the Notes Cover

• Work done by a constant force, and the sign convention that goes with it
• Work by a variable force, as an integral and as the area under a graph
• The spring force and the half k x squared it stores
• Kinetic energy and the work-energy theorem, which holds for any force at all
• Potential energy, conservative and non-conservative forces, and F = minus dU by dx
• Conservation of mechanical energy, and what friction does to it
• Motion in a vertical circle, including the string and rod conditions
• Power, average and instantaneous

How to Approach the Chapter

The habit worth building is reaching for energy before Newton. If a question gives two positions and asks for a speed, the work-energy theorem gets there in one line where equations of motion take four.

The theorem is also more general than students expect. It holds whether the forces are constant or varying, conservative or not, so long as you count every force in the net work. Friction and tension included.

Vertical circles are the part that feels hardest and is not. They are an energy question with one extra equation: at the top, gravity and tension both point inward, and the limiting case is when the tension reaches zero.

Common Mistakes

• Multiplying by the final force when the force varies. Integrate, or take the area
• Forgetting that a porter carrying a case on level ground does no work against gravity
• Giving friction a potential energy. Only conservative forces have one
• Using root 5gL for a rod. A rod can push, so its condition is 4gL
• Treating the kilowatt-hour as a power. It is an energy
• Assuming a car at constant speed needs no power. It needs exactly enough to beat drag

Video Revision

Source: JEE Wallah

How to Use These Notes

Read a page, close it, and write the boxed formula from memory before turning over. The notes are deliberately short per page so that is possible.

The last three pages are a mistake list and twelve practice questions with worked answers. Do those before any coaching sheet: they are chosen so each one teaches a move the rest of the chapter reuses.

Collisions belong to this same unit and have their own set of notes, together with centre of mass.