What is Work (in Physics)?
Work is the energy transferred to an object when a force moves it through a distance. Pushing a box across the floor, lifting a weight, or a crane hoisting a beam are all examples of work being done.
Work equals force times displacement in the direction of the force: W = F·d, measured in joules (J). If the force and displacement are at an angle, only the parallel component counts: W = F·d·cosθ.
Try it: interactive calculator
Step-by-step worked examples
A 50 N force pushes a box 4 m in the direction of the force. Find the work done.
W = F · d W = 50 × 4 W = 200 J
A 10 kg mass is lifted straight up 2 m. Find the work done against gravity (g = 9.8 m/s²).
F = mg = 10 × 9.8 = 98 N W = F · d = 98 × 2 W = 196 J
A 30 N force is applied at 60° to a 5 m displacement. Find the work done.
W = F · d · cos θ W = 30 × 5 × cos(60°) W = 150 × 0.5 W = 75 J
Flashcards
Quick quiz
Q1.What is the formula for work when force and displacement are parallel?
Q2.What is the SI unit of work?
Q3.If a force is perpendicular to the displacement, the work done is...
Q4.A 100 N force moves an object 3 m in its own direction. What is the work done?
The full card deck, worked steps and AI-tutor support for “What is Work (in Physics)?” are in Notek — study by hand before your exam.
Common mistakes
Thinking work and force are the same quantity. — Correct: Work (J) = force (N) × displacement (m); they have different units and meanings.
Confusing work with power. — Correct: Power is the rate of doing work: P = W/t, measured in watts, not joules.
Ignoring the angle between force and displacement. — Correct: Only the component of force parallel to the motion does work: W = F·d·cosθ.
Assuming any applied force always does work. — Correct: If there's no displacement (like holding a bag still) or the force is perpendicular to motion, the physics work is zero.
FAQ
What is the formula for work in physics?
W = F·d for a force parallel to displacement, or W = F·d·cosθ if there's an angle between them. Unit: joule (J).
How do you calculate work done by a force?
Multiply the force (N) by the displacement (m) in the direction of that force.
What are examples of work in physics?
Pushing a shopping cart, lifting a box, or a crane hoisting a beam are all examples of work being done.
What is the difference between work and energy?
Work is the process of transferring energy via a force; energy is the capacity to do work. Both are measured in joules.