Table of Contents
What Is Work?
In physics, work is energy transferred by a force acting through a displacement. Work = force × distance when force is parallel to motion. At an angle, only the parallel component does work. No displacement means no work, regardless of force magnitude.
Work is measured in joules (1 J = 1 N·m). It is a scalar quantity that can be positive (force aids motion) or negative (force opposes motion, like friction).
Formula
At 0°: maximum work. At 90°: zero work (perpendicular force). At 180°: negative work (opposing force).
Everyday Work Examples
| Activity | Force (N) | Distance (m) | Work (J) |
|---|---|---|---|
| Lift book 1m | 9.81 | 1.0 | 9.81 |
| Push cart 10m | 50 | 10 | 500 |
| Climb stairs (70kg, 3m) | 687 | 3.0 | 2,060 |
Frequently Asked Questions
Is holding a heavy object work?
No. Physics work requires displacement. Holding a weight stationary does no mechanical work. Your muscles fatigue from internal biological processes, but no work is done on the object.
What is the work-energy theorem?
Net work equals change in kinetic energy: W_net = ½mv² - ½mv₀². This connects force, displacement, and motion.
Can work be negative?
Yes. Friction does negative work (opposes motion). Negative work removes kinetic energy, converting it to heat.