LuduminaFM-06 · FM-U2 · Planned
Work against friction
Learning objectives
Calculate work along the force direction; link frictional work to thermal changes.
DfE single-science pp.35–37 / Combined pp.30–32. Evidence checked 30 September–1 October 2026. Skills: WS3.6,4.5; MS3b,3c.
Explanation
A pulling force can do work even when speed is steady. At steady speed its force may balance resistance, while energy continues to transfer into internal energy through friction. Zero net force does not imply zero work by each individual force.
Concepts, equations and units: W_work=Fs; J=N m; F in N, s in m; constant force along displacement.
Prediction, demonstration and game exercise
Predict, observe, explain
Pull a crate at steady speed; compare force and thermal-energy ledgers on two surfaces.
Planned learner game exercise
Move a crate a fixed distance using a force meter; tune lubrication and reconcile the energy difference.
Independent practice
Three work calculations and an explanation of steady-speed energy transfer.
Original practice example · Shared
A constant 15 N pulling force moves a crate 4 m along the force direction. Find work done by the pull.
Show working and model answer
Working / reasoning
W_work = Fs = 15 × 4.
Answer
60 J; at steady speed this can be matched by work against resistance.
Exit check and success criteria
Two calculations correct and thermal destination named; distinguish balanced forces from zero transfer.
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
Steady speed means no work done by the pulling force; friction destroys energy.
Practical preparation
Optional friction/work study, AT2,5.
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.