Work
Work is force times distance in the direction of the force.
About this topic
In physics, work is done when a force moves an object in the direction of the force: W = Fd cos θ, measured in joules. Carrying a bag horizontally does no work on it since the force is perpendicular to the motion.
Work is positive when the force helps the motion, negative when opposing it, such as friction, and it transfers energy. One joule is the work done by a force of 1 N moving an object 1 m. If the force varies, work is the area under a force-distance graph. No movement means no work, however tired you feel.
Example: pushing a 20 N crate 5 m with a horizontal force of 20 N does 100 J. Pulling a sled with a rope at 30 degrees with 50 N over 10 m does 50 x 10 x cos 30, about 433 J. A weightlifter holding a barbell still does no work on it in the physics sense, although the muscles consume energy internally. Cranes, engines and bicycles all do work to change energy.
Common mistakes: forgetting the cosine factor, using the total distance when the object returns, and thinking that force alone means work. Only the component along the displacement counts.
Key ideas
- W = F d cos θ
- Unit: joule
- No displacement means no work
Quick check
Use cases: where Work helps
- Homework: review the key idea behind Work before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Work without notes.
- Visual learning: play with the interactive lab to see how Work changes when you adjust its inputs.
- Teaching a friend: explain Work in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Work?
Work is force times distance in the direction of the force.
What will I learn in Work?
W = F d cos θ. Unit: joule. No displacement means no work.
Is Work part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Work lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Work?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.