Physics
Work done and the change in energy
Net work equals the change in kinetic energy. It is the bridge between a force acting over a distance and the energy an object ends up carrying.
The Formula
W = F d = Delta KE
Net work equals the change in kinetic energy. It is the bridge between a force acting over a distance and the energy an object ends up carrying.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| W | Work done on the object | joules | One joule of net work changes kinetic energy by one joule. |
| F | Force applied | newtons | Taken along the direction of motion. |
| d | Distance over which the force acts | metres | This is why doubling the energy roughly doubles the braking distance. |
What Each Symbol Means
Wjoules
Work done on the object
One joule of net work changes kinetic energy by one joule.
Fnewtons
Force applied
Taken along the direction of motion.
dmetres
Distance over which the force acts
This is why doubling the energy roughly doubles the braking distance.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate kinetic energy page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Kinetic Energy, filed under Science. Every number the guide produces comes from substituting into this one line.