LuduminaEN-06 · EN-U2 · Planned
Elastic energy
Learning objectives
Calculate elastic energy within the proportional range; distinguish extension from total spring length.
8463 §§4.1.1.2,4.5.3 / 8464 §§6.1.1.2,6.5.3
DfE single-science pp.34–35 / Combined pp.29–30. Evidence checked 30 September–1 October 2026. Skills: WS1.2,4.5; MS3c.
Needs firstEN-05; P0 squares
Explanation
Extension is the change from the spring’s unloaded length. The elastic-energy equation used here assumes the proportional range, so a spring cannot be treated as an unlimited energy store obeying the same rule at every stretch.
Concepts, equations and units: E_e = ½ke²; J; k in N/m, e in m. Equation conditional on proportional behaviour.
Prediction, demonstration and game exercise
Predict, observe, explain
Stretch/compress springs with different stiffness; mark original length and linear limit.
Planned learner game exercise
Choose k and extension to store a safe target energy; reject model settings beyond the stated validity range.
Independent practice
Calculate three energies and predict the effect of doubling extension; connect to force data later in FM-05.
Original practice example · Shared
A spring has k = 200 N/m and extension 0.10 m within its proportional range. Find stored energy.
Show working and model answer
Working / reasoning
E_e = ½ke² = ½ × 200 × 0.10².
Answer
1.0 J.
Exit check and success criteria
Two calculations correct, extension measured correctly and validity condition stated.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Use total length; all springs obey the formula for every extension.
Practical preparation
Preparation bridge to RP-P6/RP-C18 in FM-05; not completion here.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.