CLASS 11 PHYSICS

Work, Energy and Power

Connect force and displacement to energy transfer and rate of work.

Learning objective

Apply work-energy ideas to mechanical systems.

State Board to NCERT bridge

From everyday effort to a precise definition involving force and displacement.

Tamil concept bridge

Work enbadhu force irundhaal mattum alla; displacement-in direction-um mukkiyam.

GUIDED LESSON

Learn the chapter step by step

Read one concept, explain it in your own words, then connect it to the formula or situation that follows. Do not try to memorise the chapter as isolated definitions.

Work is the scalar product W = Fs cos theta. Only the component of force along displacement does work; a perpendicular force does zero work.

Tamil support: Work enbadhu force irundhaal mattum alla; displacement-in direction-um mukkiyam.

Ask yourself: Can I give one everyday example of work by a force?

WORKED EXAMPLE

Kinetic energy

Given: A 2 kg object moves at 4 m/s.

1Use K = 1/2 mv^2.
2Substitute m = 2 kg and v = 4 m/s.
3K = 1/2 x 2 x 4^2.

Answer: Kinetic energy = 16 J.

FORMULA / FACT BANK

Know what each relationship means

Work

W = Fs cos theta

Constant force.

Kinetic energy

K = 1/2 mv^2

Energy due to motion.

Memory cue: positive and negative work · work-energy theorem · conservation · power

SELF-CHECK

Which concept should you start with?

Choose the core foundation concept for this chapter.

COMMON MISTAKES

Do not use a formula before identifying the physical quantities and their SI units.
Keep direction, sign convention and stated conditions visible throughout a solution.
Check whether your answer has a sensible unit and magnitude.

REVISION PLAN

1. Re-read the visual summary and say each revision target aloud.
2. Redo the worked example without looking at the steps.
3. Complete the 80-question bank and revisit every incorrect explanation.

VISUAL NOTES