Numbers
AQA A-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Electricity
Further Mechanics and Thermal Physics
Fields and Their Consequences
Topic overviewFieldsNewton's lawGravitational field strengthGravitational potentialOrbits of planets and satellitesCoulomb's lawElectric field strengthElectric potentialCapacitanceParallel plate capacitorEnergy stored by a capacitorCapacitor charge and dischargeMagnetic flux densityMoving charges in a magnetic fieldMagnetic flux and flux linkageElectromagnetic inductionAlternating currentsTransformers
Nuclear Physics
AstrophysicsOptional topic
Topic overviewAstronomical telescope consisting of two converging lensesReflecting telescopesSingle dish radio telescopes, I-R, U-V and X-ray telescopesAdvantages of large diameter telescopesClassification by luminosityAbsolute magnitude, MClassification by temperature, black-body radiationPrinciples of the use of stellar spectral classesThe Hertzsprung-Russell (HR) diagramSupernovae, neutron stars and black holesDoppler effectHubble's lawQuasarsDetection of exoplanets
Medical PhysicsOptional topic
Topic overviewPhysics of visionDefects of vision and their correction using lensesEar as a sound detection systemSensitivity and frequency responseDefects of hearingSimple ECG machines and the normal ECG waveformUltrasound imagingFibre optics and endoscopyMagnetic resonance (MR) scannerThe physics of diagnostic X-raysImage detection and enhancementAbsorption of X-raysCT scannerImaging techniquesHalf-lifeGamma cameraUse of high-energy X-raysUse of radioactive implantsImaging comparisons
Engineering PhysicsOptional topic
Turning Points in PhysicsOptional topic
Topic overviewCathode raysThermionic emission of electronsSpecific charge of the electronPrinciple of Millikan's determination of the electronic charge, eNewton's corpuscular theory of lightSignificance of Young's double slits experimentElectromagnetic wavesThe discovery of photoelectricityWave–particle dualityElectron microscopesThe Michelson-Morley experimentEinstein's theory of special relativityTime dilationLength contractionRelativistic mass and energy
ElectronicsOptional topic
Topic overviewMOSFET (metal-oxide semiconducting field-effect transistor)Zener diodePhotodiodeHall effect sensorDifference between analogue and digital signalsLC resonance filtersThe ideal operational amplifierInverting amplifier configurationNon-inverting amplifier configurationSumming amplifier configurationReal operational amplifiersCombinational logicSequential logicAstablesPrinciples of communication systemsTransmission mediaTime-division multiplexingAmplitude (AM) and frequency modulation (FM) techniques
Mechanics and Materials
Work, energy and power
- 5 things to know
- Papers 1 and 3
Overview
Work done by a force at an angle, power, efficiency, and the area under a force-displacement graph.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What is power, and how is it calculated from work and time?
Numbers
How is power found from force and velocity, and why can W = Fs fail?
Numbers
How is work found from a force-displacement graph?
Numbers
How is efficiency calculated, and in what forms can it be expressed?
Questions from this subtopic
Each one with the model answer underneath.
- 1
In the equation W = Fs cos θ, what does W represent?
Model answer
W represents the work done, which is the energy transferred.
- 2
Why is the cos θ term included in the work equation W = Fs cos θ?
Model answer
The cos θ term accounts for the component of the force acting in the direction of motion.
- 3
Calculate the work done when force = 53 N, displacement = 35.4 m, angle = 5 degrees.
Model answer
Work done = 53 × 35.4 × cos 5° = 1870 J.
- 4
When a force acts parallel to the displacement, what is the value of θ and what does the work equation simplify to?
Model answer
θ = 0°, cos θ = 1, so the equation simplifies to W = Fs.
- 5
Why is no work done when a force acts perpendicular to the displacement?
Model answer
When θ = 90°, cos θ = 0, so W = Fs × 0 = 0. There is no component of force in the direction of motion.
- 6
Define power.
Model answer
Power is the rate of doing work, or equivalently, the rate of energy transfer.
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