What is Work Done in Physics?
In everyday language, "work" means anything that takes effort. But in physics, work has a very specific meaning — it only happens when a force causes an object to move in the direction of that force.
Work done is the energy transferred to or from an object when a force causes it to move through a distance. It is calculated as the product of the force applied and the distance moved in the direction of that force.
This means that if you push against a wall all day and it doesn't move, you have done zero work in the physics sense — even though you feel exhausted! Energy is only transferred when movement actually occurs.
Think of carrying a heavy bag horizontally across a room. You're exerting an upward force to hold the bag, but the movement is horizontal — these are perpendicular directions. Technically, your holding force does no work on the bag! The work is done only by the horizontal push that actually moves the bag forward.
Work done is measured in joules (J), the same unit as energy — which makes perfect sense, since work is a transfer of energy.
The Work Done Formula
The formula for work done is one of the most important in this unit:
Where:
- = work done (joules, J)
- = force applied (newtons, N)
- = distance moved in the direction of the force (metres, m)
The distance must always be measured in the direction of the applied force. If a force is applied at an angle, only the component of distance in the force's direction counts. At MYP 4 level, you will typically deal with forces and motion in the same direction, so applies directly.
You can rearrange this formula to find force or distance if needed:
A useful memory trick: think of Work = Force × distance as "Waiting For dinner" — silly, but it works!
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