HelpContactFor teachers and institutes
>_StemPy Lab
Mock TestsClasses

>_StemPy Lab

Learn. Solve. Code the solutions. Test yourself.

Live examsFree mock exams, timed and rankedEveryone starts together, and your score and rank come the moment it ends.See the exams →

Learn

  • Physics
  • Chemistry
  • Mathematics
  • Biology
  • Python Programming
  • Statistics & Data Science
  • Classes
  • Groups

Practice

  • Problems
  • Quizzes
  • Mock Tests
  • Prepare for an Exam
  • Question Sets
  • Exams
  • Certificates
  • Python Labs
  • AI Practice Generator
  • Student-Created Tests

Community

  • Discussions
  • Resources
  • Notes
  • Glossary
  • Blog

Account

  • Log in
© 2026 senLearn. All rights reserved.HelpAboutContactPrivacy PolicyTerms of UseRefund Policy
  1. Glossary
  2. /Physics
  3. /Work and Power

What is Work and Power?

In short

Work is done when a force moves an object, W=Fdcos⁡θW = Fd\cos\thetaW=Fdcosθ, and it is measured in joules. Power is the rate of doing work, P=WtP = \dfrac{W}{t}P=tW​, measured in watts.

In simple words

Only the part of the force along the displacement does work. A force at right angles to the motion, such as the pull of the Sun on a planet in a circular orbit, does no work. One watt is one joule per second. A kilowatt-hour is the energy used by a 1 kW1\ \text{kW}1 kW appliance in one hour, which is 3.6×106 J3.6 \times 10^{6}\ \text{J}3.6×106 J.

Example

A crane lifts a 200 kg200\ \text{kg}200 kg load by 15 m15\ \text{m}15 m in 30 s30\ \text{s}30 s. Work =200 kg×9.8 m/s2×15 m=29 400 J= 200\ \text{kg} \times 9.8\ \text{m/s}^2 \times 15\ \text{m} = 29\,400\ \text{J}=200 kg×9.8 m/s2×15 m=29400 J, so the power is 29 400 J30 s=980 W\dfrac{29\,400\ \text{J}}{30\ \text{s}} = 980\ \text{W}30 s29400 J​=980 W.

Learn it properly

  • Lessons on this topic
  • Practise problems
  • Test yourself

Related terms

  • Kinetic Energy and Potential Energy
  • Friction

← All glossary terms

Learn it in

  1. Work and Its MeasurementClass 9 to 10
  2. Kinetic and Potential EnergyClass 9 to 10
  3. Conservation of Energy and PowerClass 9 to 10
All lessons on this topic →

Practise

  1. A block of mass 1.0 kg lies on a rough horizontal floor…Hard
  2. A truck of mass 3000 kg has an engine that delivers a constant power of 60 kW to the…
Advanced
  • A particle of mass 0.50 kg moves along the positive x-axis…Hard
  • A block of mass M = 4.0 kg rests on a smooth horizontal floor…Advanced
    • All problems on this topic →

    Quick questions

    1. A block on a spring is let go from one end of its swing. How long after that are its…Hard
    2. A spring of 560 N/m carries a block that swings with an amplitude of 3.0 cm. What is the…Medium
    3. A block on a spring swings 16.5 cm each way. At one point of its path it has eight times…Medium

    More Physics terms

    1. Acceleration
    2. Acceleration Due to Gravity (g)
    3. Adiabatic Process
    4. Amplitude
    5. Angle of Incidence
    6. Angle of Reflection
    All Physics terms →

    Preparing for an exam?

    Pick your exam to see its syllabus, where you stand in each unit and what to practise next.

    See exam preparation