Physics
Work (Physics)
Quick fact
Work is only done when the force causes displacement in the same direction; holding a heavy object stationary does no work, despite effort.
Why this is interesting
You feel tired after pushing a wall for hours, but physics says you did zero work. Why?
Read the full explanation
Understanding Work (Physics)
In physics, work has a specific meaning: it happens when a force moves an object over a distance. Imagine pushing a shopping cart: you apply a force, and the cart moves forward—that's work. But if you push against a wall that doesn't move, no work is done because there is no displacement. Work is calculated as force multiplied by the distance moved in the direction of the force. If you push at an angle, only the part of the force that points along the movement counts. The formula is Work = Force × Displacement × cos(θ), where θ is the angle between the force and the displacement. Work is measured in joules (J), the same unit as energy.
A deeper explanation
Work is a mechanism for transferring energy. When you do positive work on an object, you add energy to it—for example, lifting a box increases its gravitational potential energy. Negative work (when the force opposes the motion) removes energy, like friction slowing a sled. The work-energy theorem states that the net work done on an object equals its change in kinetic energy. This principle connects force and motion to energy, explaining why a faster moving object has more kinetic energy. Work also relates to power: power is the rate at which work is done. Understanding work deepens your grasp of machines (e.g., levers, pulleys) and why they reduce the force needed by increasing displacement.