Work done
Energy transferred when a force moves something. Work done = force x distance moved in the direction of the force.
Last updated
Analogy
Pushing a heavy box across a room: more force or more distance means more work.
Example
force = 50 Ndistance = 6 mwork = 50 x 6work = 300 J
In practice
Holding a bag still does no work in physics, because it does not move.
Practice
Flashcards
- How do you calculate work done?Work done = force x distance moved in the direction of the force.
Interview questions
- A 60 kg student climbs stairs 3 m high in 6 s. Take g = 10 N/kg. Calculate the work done and the power.
- Gain in GPE = 60 x 10 x 3 = 1,800 J
- Work done equals the energy transferred, 1,800 J
- Power = 1,800 / 6 = 300 W
Questions people ask
Why is holding a heavy bag still not work in physics?
Work is force multiplied by distance moved. If the bag stays still, the distance is zero, so the work done is zero. Your muscles do get tired, because they keep using chemical energy inside the muscle, but no energy is transferred to the bag.
How is work done linked to energy?
Work done is the energy transferred. If you do 300 J of work pushing a crate against friction, 300 J moves from your chemical store to the crate and floor, mostly as thermal energy. The two quantities share the same unit, the joule.