1. Work and Variable Force
Work done by a force is the scalar product of force and displacement:
If the force varies with position, use the integral form . This is why area under an - graph is such an important visual tool in JEE.
JEE Main & Advanced / Physics / Chapter 7
Work, Power and Energy
Learn how JEE turns mechanics into energy bookkeeping: work by variable force, conservative fields, power, and the work-energy theorem.
Original Notes2 Core SectionsJEE Revision Style
Ad Slot: Top Navigation Leaderboard
JEE Intro
How to Think About Work, Power and Energy
Learn how JEE turns mechanics into energy bookkeeping: work by variable force, conservative fields, power, and the work-energy theorem.
This chapter is written as original Learn at My Place teaching copy. The aim is to give you the JEE decision-making layer: what equation to trust, what approximation is valid, and where exam traps usually appear.
Read the full note once, then revisit the quick revision block before solving your own practice questions.
Problem Method
How to Solve Work, Power and Energy Questions
1. Model the Situation
Draw the body, path, field, graph, or interaction first. Label known quantities and choose sign convention before writing equations.
2. Pick the Governing Law
Decide whether the problem is about conservation, force balance, energy, momentum, fields, or graph interpretation.
3. Check the Edge Case
Verify units, limiting values, direction, and whether approximation assumptions are valid for JEE Main and Advanced options.
Section A
Notes: Work, Power and Energy
Original teaching copy for Learn at My Place
2. Work-Energy Theorem and Power
The net work done on a particle equals the change in kinetic energy:
For conservative forces, define potential energy so that , then total mechanical energy becomes . Power measures rate of doing work and at any instant:
Choose the energy route when force details are messy but speeds or heights are asked.
Quick Revision
Last 5-Minute Recall
JEE exam rule: First identify the governing principle. Most errors happen because students choose the wrong framework before they start the algebra.
Positive, negative, and zero work
Work-energy theorem for quick numerical solutions
Potential energy and conservative forces
Power in constant and variable force cases
Verified question bank
Work, Power and Energy questions with answers
Open any of these 83 quality-checked JEE questions to review all four options, the correct answer, and the worked explanation.
- Question 1 · EasyWork Definition
- Question 2 · EasyWork — Perpendicular Force
- Question 3 · EasyWork — Negative Work
- Question 4 · EasyKinetic Energy
- Question 5 · EasyWork-Energy Theorem
- Question 6 · EasyPotential Energy — Gravity
- Question 7 · EasySpring PE
- Question 8 · EasyPower Definition
- Question 9 · EasyConservative Force
- Question 10 · MediumWork — Variable Force
- Question 11 · MediumEnergy Conservation
- Question 12 · MediumPower — Instantaneous
- Question 13 · MediumWork by Friction
- Question 14 · EasyUnits of Work/Energy
- Question 15 · MediumKinetic Energy — Momentum
- Question 16 · MediumSpring Work
- Question 17 · MediumGravitational PE — Change
- Question 18 · HardWork — Angle Calculation
- Question 19 · EasyPower — Units
- Question 20 · MediumNon-conservative Force
- Question 21 · MediumProjectile Energy
- Question 22 · MediumEnergy — Incline
- Question 23 · MediumPower — Engine
- Question 24 · MediumSpring — Compression
- Question 25 · MediumConservative Force — PE
- Question 26 · HardWork-Energy — Incline with Friction
- Question 27 · HardElastic Collision — Energy
- Question 28 · MediumPower — Lift
- Question 29 · MediumPotential Energy — Graph
- Question 30 · HardEnergy — Spring-Block
- Question 31 · EasyWork by Normal Force
- Question 32 · MediumKinetic Energy Change
- Question 33 · HardStopping Distance
- Question 34 · MediumConservative Field
- Question 35 · MediumPower — Running
- Question 36 · HardEscape KE
- Question 37 · HardPower — Variable Force
- Question 38 · HardInelastic Collision — Energy Loss
- Question 39 · HardSpring Energy — Two Compressions
- Question 40 · MediumEnergy — Conceptual
- Question 41 · HardRoller Coaster
- Question 42 · HardSpring — Collision
- Question 43 · MediumWork done against gravity
- Question 44 · HardVariable Force Work
- Question 45 · MediumMechanical Energy — Pendulum
- Question 46 · MediumPower — Speed Relation
- Question 47 · HardEnergy — Block on Spring
- Question 48 · MediumWork — Multiple Forces
- Question 49 · HardEscape Speed Using Energy
- Question 50 · HardCoefficient of Restitution
- Question 51 · HardPower — Slope
- Question 52 · HardEnergy Loss — Inelastic
- Question 53 · HardPE Function
- Question 54 · MediumWork — Friction on Incline
- Question 55 · HardSpring — Two Blocks
- Question 56 · MediumKinetic Energy — Relative
- Question 57 · MediumPower at Terminal Velocity
- Question 58 · HardWork — Spring Not at Origin
- Question 59 · MediumJEE — Energy on Circular Path
- Question 60 · HardJEE — Block on Wedge Energy
- Question 61 · MediumJEE — Power as Rate of Energy
- Question 62 · HardJEE — PE Curve
- Question 63 · HardJEE — Elastic Head-on
- Question 64 · HardJEE — Spring Vertical
- Question 65 · MediumJEE — Power Dissipation
- Question 66 · MediumJEE — Horizontal Projection KE
- Question 67 · HardJEE — Spring-Block Period and Energy
- Question 68 · HardJEE — Non-conservative Work
- Question 69 · MediumJEE — Work in Circular Motion
- Question 70 · MediumJEE — Efficiency
- Question 71 · HardJEE — Mass-Energy Equivalence
- Question 72 · HardJEE — Energy Stored in Spring Pair
- Question 73 · HardAdvanced — Head-on Elastic
- Question 74 · HardAdvanced — Oblique Collision
- Question 75 · HardAdvanced — Potential Well
- Question 76 · HardAdvanced — Energy Method for Oscillation
- Question 77 · HardAdvanced — Rocket Propulsion
- Question 78 · HardAdvanced — Bead on Wire
- Question 79 · HardAdvanced — Work Theorem with PE
- Question 80 · HardAdvanced — Maximum Height
- Question 81 · HardAdvanced — Variable Force Integration
- Question 82 · HardAdvanced — Power in Rotational System
- Question 83 · HardAdvanced — Bound and Unbound States
Finished this topic?
Keep the practice loop moving
Move straight from chapter-wise questions into a subject test, then loop back into weaker areas instead of ending the session here.