Work in physics: force times distance
In everyday speech "work" is effort. In physics it is precise: a force does work only when it moves something along its own direction.
F is the force in newtons, d the distance in metres, and θ the angle between them. Push a box 3 m with 20 N in the direction of travel and you do 60 joules of work.
No motion, no work
Because work needs distance, holding a weight still does zero physical work — your muscles tire, but nothing moves, so W = 0. Likewise a force at right angles to the motion (cos 90° = 0) does no work.
Work and energy are the same currency
Work is measured in joules, exactly like energy, because doing work transfers energy. Lift a book and you spend work that becomes the book's stored (potential) energy — the calculator shows that transfer as a number.
Frequently asked questions
What is the work formula in physics?
Work equals force times the distance moved in the direction of the force: W = F·d. With an angle between them, W = F·d·cosθ. The result is in joules.
What are the units of work?
The joule (J), the same unit as energy. One joule is one newton-metre: the work done pushing with one newton over one metre.
Is work done if nothing moves?
No. If the distance is zero, the work is zero, no matter how hard you push. Holding a heavy box still is tiring but does no physical work in the scientific sense.
What is the difference between work and energy?
Work is the transfer of energy by a force. They share the same unit, the joule: doing work on an object changes its energy by the same amount.
Why does the angle matter?
Only the part of the force along the direction of motion does work, which is where cosθ comes in. A force at right angles to the motion (θ = 90°) does no work at all.