KTUYSBeta
Log inSign up

Cheat sheet · JEE Preparation Physics

Work, Energy and Power cheat sheet

The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.

JEE · Physics

Cheat sheet

Class 11 · Chapter 5Work, Energy and Power

Work done by net force = change in kinetic energy (work–energy theorem).

1. Work

W=F⃗⋅d⃗=Fdcos⁡θW = \vec F\cdot\vec d = Fd\cos\theta
W=∫F dxW = \int F\,dx (variable force)

Work is positive for θ < 90°, zero for θ = 90°, negative for θ > 90°.

2. Energy

K=12mv2=p22mK = \tfrac{1}{2}mv^2 = \dfrac{p^2}{2m}
U=mghU = mghUspring=12kx2U_{spring} = \tfrac{1}{2}kx^2

Work–energy theorem: Wnet=ΔKW_{net} = \Delta K.

Conservative force: work independent of path (gravity, spring). Mechanical energy K + U is conserved.

3. Power

P=dWdt=F⃗⋅v⃗P = \dfrac{dW}{dt} = \vec F\cdot\vec v

1 W = 1 J/s; 1 hp = 746 W; 1 kWh = 3.6 × 10⁶ J.

4. Collisions

TypeMomentumKinetic energy
Elasticconservedconserved
Inelasticconservednot conserved
Perfectly inelasticconservedmax loss; bodies stick

1-D elastic, equal masses: velocities are exchanged.

5. Key Points

  • Work by friction is negative.
  • Centripetal force does no work.
  • Spring force F = −kx (Hooke's law).
  • Momentum is conserved in every collision.

Remember: W = Fd cosθ | W_net = ΔK | P = Fv | elastic vs inelastic

Work, Energy and Power: questions and notes

More JEE Preparation Physics cheat sheets

Practise Work, Energy and Power

Sign up free to practise the full chapter. Questions you get wrong come back until you've mastered them.

Start practising free

Free to start · No credit card needed