6.2.4—EP = 1/2 Fx = 1/2 kx2 for a material deformed within its limit of
- Syllabus
- 9702–2028–2029
- Objective
- 6.2.4
- Level
- AS
For a linear spring, elastic potential energy is ½Fx or ½kx²
Within the proportional region, E_P=½Fx=½kx² because the average force during loading is F/2.
Use final force and extension only for a straight-line force–extension graph from zero. For a non-linear graph, find the area under the curve.
A spring with k=200 N m⁻¹ stretched 0.10 m stores 1.0 J.
Do not use Fx for a spring whose force changes during loading; that would overestimate the work by a factor of two in the linear case.
ConceptA-Level CAIE Physics AS