Work, Energy and Power Class 11: All Formulas & Formula Sheet with Free PDF Download (Physics, JEE & NEET)
Work, Energy & Power Class 11 Formula Sheet — Competishun
Work, Energy and Power Class 11: All Formulas & Formula Sheet with Free PDF Download (Physics, JEE & NEET)
Work, Energy and Power is one of the most important chapters in Class 11 physics, and one of the highest scoring for JEE and NEET. It ties together force and motion through the powerful idea of energy, and introduces tools like the work-energy theorem and conservation of energy that you will use for the rest of physics.
This page gives you the complete Work, Energy and Power formula sheet for Class 11 in one place: all formulas for work, kinetic and potential energy, power, conservation of energy and collisions, with worked examples. Download the free PDF below and keep it handy for revision.
Download the Work, Energy & Power Formula Sheet PDF
Get all Work, Energy and Power formulas, the work-energy theorem, conservation of energy and collisions in one clean PDF, free. Perfect for Class 11, JEE and NEET revision.
Download Free PDFWork, Energy & Power: Quick Definitions
| Quantity | Meaning | SI Unit |
|---|---|---|
| Work | Energy transferred when a force moves an object | Joule (J) |
| Energy | Capacity to do work (kinetic + potential) | Joule (J) |
| Power | Rate of doing work / transferring energy | Watt (W) |
| Work is done, energy is stored, power is how fast. All are scalar quantities. | ||
1. Work Formulas
| Case | Formula |
|---|---|
| Constant force | W = F·s·cosθ = F⃗ · s⃗ |
| Force along motion (θ=0) | W = F·s |
| Perpendicular force (θ=90°) | W = 0 |
| Variable force | W = ∫ F dx (area under F-x graph) |
| Work by gravity | W = ± mgh |
| Work by spring | W = ½k x² |
| Work is positive if force aids motion, negative if it opposes (like friction), and zero if perpendicular. | |
2. Energy Formulas
| Type | Formula |
|---|---|
| Kinetic energy | KE = ½ m v² |
| KE and momentum | KE = p² / 2m (p = mv) |
| Gravitational PE | PE = m g h |
| Spring (elastic) PE | PE = ½ k x² |
| Work-energy theorem | W(net) = ΔKE = ½mv² − ½mu² |
| Mechanical energy | E = KE + PE |
| The work-energy theorem is the most useful result here: net work equals the change in kinetic energy. | |
3. Power Formulas
| Type | Formula |
|---|---|
| Average power | P(avg) = Work / time = W / t |
| Instantaneous power | P = F⃗ · v⃗ = F v cosθ |
| Power and energy | P = dE / dt |
| Unit conversions: 1 W = 1 J/s, 1 HP = 746 W, 1 kWh = 3.6 × 10⁶ J. | |
4. Conservation of Energy
When only conservative forces (like gravity or spring force) act, the total mechanical energy stays constant.
| Force Type | Property |
|---|---|
| Conservative (gravity, spring) | Work is path independent, mechanical energy conserved |
| Non-conservative (friction) | Work is path dependent, mechanical energy not conserved |
| Energy is never lost overall, it only converts, for example into heat when friction acts. | |
5. Collisions
| Concept | Formula / Rule |
|---|---|
| Momentum (always conserved) | m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ |
| Coefficient of restitution | e = (v₂ − v₁) / (u₁ − u₂) |
| Elastic collision | e = 1, KE conserved |
| Perfectly inelastic | e = 0, bodies stick together |
| Inelastic collision | 0 < e < 1, some KE lost |
| Momentum is conserved in all collisions. Kinetic energy is conserved only in perfectly elastic collisions. | |
Worked Examples
| Problem | Solution |
|---|---|
| Work by 10 N over 5 m (θ=0) | W = 10 × 5 = 50 J |
| KE of 2 kg at 3 m/s | KE = ½ × 2 × 3² = 9 J |
| PE of 5 kg at 4 m (g=10) | PE = 5 × 10 × 4 = 200 J |
| Power: 600 J in 3 s | P = 600 / 3 = 200 W |
| Speed from KE (9 J, 2 kg) | v = √(2×9/2) = 3 m/s |
| Most problems are solved by picking the right formula and plugging in consistent SI units. | |
Common Mistakes to Avoid
- Forgetting cosθ: Work uses the angle between force and displacement, not just F × s
- Sign of work: Friction and opposing forces do negative work
- Mixing energy and power: Energy is in joules, power is joules per second (watts)
- KE vs momentum: KE = ½mv² is scalar, momentum p = mv is a vector
- Assuming KE is always conserved: It is conserved only in elastic collisions, momentum always is
Why This Chapter Matters for JEE & NEET
- High weightage: Work, Energy and Power appears every year in JEE Main, Advanced and NEET
- Powerful shortcuts: Energy methods solve many problems faster than force methods
- Foundation for more: Used in SHM, gravitation, rotational motion and thermodynamics
- Scoring topic: Clear formulas make it one of the most reliable chapters for marks
How to Use This Formula Sheet
- Learn the core three: Work (F·s cosθ), KE (½mv²) and Power (F·v)
- Master the work-energy theorem: It is your fastest tool for speed problems
- Practise collisions: Always start from momentum conservation
- Revise from the PDF: Skim it before every physics test and mock
Get the Complete Formula Sheet PDF Free
Download the full Work, Energy and Power Class 11 formula sheet and revise anytime, anywhere.
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