Work, Power and Efficiency
Calculate mechanical, gravitational, kinetic and elastic energy changes, power and efficiency.
How to study for GCSE Physics
Move deliberately among physical models, diagrams, equations, units, graphs, experiments and evaluation; finish with the exact paper and practical structure named by your exam board.
Core concepts
Concept 1
Work done is energy transferred when a force moves through a distance along its line of action.
Exam cue: Choose the energy relationship, convert units, calculate, then test magnitude and efficiency bounds.
Concept 2
Power is the rate of energy transfer or work done.
Exam cue: Distinguish joules from watts and state whether the ratio uses energy or power.
Concept 3
Efficiency compares useful output with total input using a consistent energy or power basis.
Exam cue: Name the physical quantities, use consistent SI units and connect the model to observable evidence.
Targeted study blocks
Tier coverage
Foundation core with Higher-tier extensions
Higher-only equations and more demanding multistep redistribution problems must be checked against the current board specification.
Risk pitfalls and guardrails
Treating power as an amount of energy.
Guardrail: Do not memorise a formula pattern without quantities, units and conditions, and do not substitute Combined Science coverage for the full separate qualification.
Substituting into an equation before identifying the system, quantities and units.
Guardrail: Do not memorise a formula pattern without quantities, units and conditions, and do not substitute Combined Science coverage for the full separate qualification.
Using a Combined Science checklist or another board's paper allocation as the separate-Physics specification.
Guardrail: Check the live specification, practical section and assessment-series support materials before final revision or timed practice.
Memory anchors
Mechanical work
Energy transferred by a force acting through a distance.
Power
Energy transferred or work done per unit time.
Efficiency
Useful output divided by total input.
Work, Power and Efficiency: method
Choose the energy relationship, convert units, calculate, then test magnitude and efficiency bounds.
Work, Power and Efficiency: check
Distinguish joules from watts and state whether the ratio uses energy or power.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
A 35 N horizontal force moves a crate 4.0 m in the force direction. How much work is done?
A lift transfers 72 kJ in 30 s. What is its mean power?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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