LuduminaEN-07 · EN-U2 · Planned
Work and power
Learning objectives
Calculate mechanical work and power; compare machines doing equal work in different times.
8463 §§4.1.1.4,4.5.2 / 8464 §§6.1.1.4,6.5.2
DfE single-science pp.34–35 / Combined pp.29–30. Evidence checked 30 September–1 October 2026. Skills: WS4.2–4.6; MS3b,3c.
Needs firstEN-04–06
Explanation
Work is energy transferred when a force causes displacement along its line of action. Power compares the rate of transfer. Two motors can do equal work while having different powers if their operating times differ.
Concepts, equations and units: W_work = Fs along force direction; P=E/t=W_work/t; J, N, m, s, W; 1 W=1 J/s.
Prediction, demonstration and game exercise
Predict, observe, explain
Two machines lift the same load; predict which is more powerful before timing them.
Planned learner game exercise
Configure a lifting machine to meet energy and time targets; maintain a ledger including friction.
Independent practice
Three work/power questions, including a rearrangement; explain why holding a stationary load does no mechanical work on it.
Original practice example · Shared
A motor lifts against 50 N through 2 m in 4 s. Find work and useful power.
Show working and model answer
Working / reasoning
W_work = Fs = 50 × 2 = 100 J; P = W_work/t = 100/4.
Answer
100 J and 25 W.
Exit check and success criteria
Two calculations with units and a correct equal-work/different-time comparison.
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
Power means total energy; weight W and work W have the same meaning; effort without displacement is work on the load.
Practical preparation
Optional load-lifting measurements, AT1,2,5.
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.