S4.9.3 For the adult
Work done
A force of 30 N moves a trolley 5 m in the direction of the force. How much work is done?
What this chapter teaches
Work done is force times the distance moved in the direction of the force, and it equals the energy transferred. A force at right angles to the movement, or on something that does not move, does no work.
Three questions to ask
There is no one right wording. Listen for the idea.
- Why does holding a heavy bag still do no work on the bag, even though you get tired?
- How do you find the work done lifting a 5 kg bag onto a shelf?
- Where does the energy go when you push a box at a steady speed across a rough floor?
After the chapter, the learner can
- Calculate work done as force times distance moved
- Explain that work done equals energy transferred
What they copy into their notebook
W = F × s, with s moved in the direction of the force. Work done = energy transferred, in J. Force at right angles, or no movement: no work. Lifting force = m × g.