H1 Physics 8867 · objective lesson
Fields and potential energy
Field work equals the negative potential-energy change; field lines show force direction and elastic energy is area under the force–extension graph.
Repair the common break
Common misconception: Positive work by a field increases potential energy.
Correct model: Field work equals the negative potential-energy change; field lines show force direction and elastic energy is area under the force–extension graph.
Worked transfer
When gravity does +50 J of work on a falling body, gravitational potential energy changes by −50 J. The sign follows Wfield = −ΔEp for the chosen system.
Guided practice
Explain why “Positive work by a field increases potential energy.” fails. Then construct one example that correctly applies fields and potential energy.
Independent practice
A spring force rises linearly from 0 to 80 N over 0.20 m. Find the stored elastic energy and state the work done by the spring during release.
Return to the recorded repair plan when the explanation and application are secure enough to re-test.