Numbers
Edexcel A-Level Physics 9PH0
Working as a Physicist
Topic overviewSI base units, derived units and homogeneityUnit prefixes, conversion and order-of-magnitude estimatesResolution, random errors and systematic errorsUncertainty and how uncertainties combineImproving measurements, graphs and evaluating resultsPeer review, publication and scientific integrityRisk, benefit and the role of science in society
Mechanics
Topic overviewThe equations of uniformly accelerated motionDisplacement-time and velocity-time graphsScalars and vectorsResolving vectors and finding resultantsProjectile motionFree-body diagrams and Newton's first and second lawsNewton's third law, mass and weightTerminal velocity and measuring g by free fallLinear momentum and its conservationElastic and inelastic collisions in one dimensionThe moment of a forceCentre of gravity, equilibrium and the principle of momentsWork done by a forceKinetic and gravitational potential energyConservation of energy and dissipationPower, and the equation P = FvEfficiency and wasted energy
Electric Circuits
Topic overviewCurrent, charge and potential differenceResistance, Ohm's law and ohmic behaviourElectrical power and energyKirchhoff's laws: the current and potential difference rulesCombining resistances in series and parallelCircuit calculations, meters and component failureI-V characteristics of conductors, lamps and diodesThermistors, light dependent resistors and resistance changeResistivity and determining it experimentallyCharge carriers, drift velocity and I = nqvAThe potential divider equation and the loading effectSensing circuits with thermistors and light dependent resistorsElectromotive force, internal resistance and lost voltsMeasuring e.m.f. and internal resistance, and cells in combination
Materials
Topic overviewDensity and how it is measuredUpthrust and Archimedes' principleFloating, sinking and upthrust calculationsViscosity, laminar flow and Stokes' lawTerminal velocity of a sphere falling through a liquidMeasuring viscosity by the falling-ball methodHooke's law, stress and strainThe Young modulus and calculations with itDetermining the Young modulus of a wireForce-extension graphs, elastic and plastic deformationStress-strain graphs, ductile and brittle materialsElastic strain energy
Waves and Particle Nature of Light
Topic overviewDescribing a progressive waveThe wave equation and its useLongitudinal and transverse wavesDisplacement-distance and displacement-time graphsMeasuring the speed of sound with an oscilloscopeWavefronts, superposition and phaseCoherence, path difference and phase differenceInterference in practiceStationary waves, nodes and antinodesHarmonics on a stretched stringInvestigating a vibrating string, and air columnsIntensity, the inverse square law and refractive indexRefraction, wave speed and the critical angleTotal internal reflection and measuring refractive indexLenses, ray diagrams and the images they formLens power and the thin lens equationLens calculations and magnificationReflection, transmission and the pulse-echo principlePulse-echo calculations, resolution and ultrasoundPolarisation and diffractionSingle-slit patterns and the diffraction grating equationGrating spectra and measuring wavelengthElectron diffraction and the de Broglie equationde Broglie calculations and wave-particle dualityPhotons and photon energyModels of light and the electronvoltLine spectra and atomic energy levelsThe photoelectric effect and Einstein's equationEvidence for the photon model and photoelectric calculations
Further Mechanics
Topic overviewImpulse and force-time graphsConservation of momentum in two dimensionsInvestigating momentum and analysing collisions on videoElastic and inelastic collisionsKinetic energy, momentum and collision calculationsThe radian, angular displacement and angular velocityAngular velocity, period and frequency of rotationCentripetal accelerationCentripetal force and what provides itVertical loops and centripetal force calculations
Electric and Magnetic Fields
Topic overviewElectric fields and electric field strengthField strength calculations and field diagramsCoulomb's law and the field of a point chargeInverse-square behaviour and combining fieldsElectric potential and field strength as a potential gradientUniform fields between parallel plates, and the potential near a point chargeEquipotentials, field diagrams and work doneCapacitance and the energy stored in a capacitorCapacitor charge and energy calculationsCharging and discharging graphs and the time constantThe exponential decay equations and logarithmic graphsInvestigating capacitor discharge and time-constant calculationsMagnetic flux density, flux and flux linkageForces on currents and moving chargesThe conditions for inducing an e.m.f.Faraday's law and Lenz's lawFlux linkage graphs and induced e.m.f. calculationsAlternating current, peak and r.m.s. valuesOscilloscope traces and alternating current calculations
Nuclear and Particle Physics
Topic overviewNuclide notation, isotopes and the alpha scattering experimentConclusions from alpha scattering and the changing model of the atomThermionic emission and linear acceleratorsThe cyclotron and the radius of a charged particle's pathParticle tracks, conservation laws and why high energies are neededMass-energy equivalence, pair production and annihilationParticle energy units and relativistic lifetimesBaryons, mesons, leptons and quark compositionThe six quarks, antiparticles and fundamental particlesConservation of charge, baryon number and lepton numberQuark changes in beta decay and testing particle equations
Thermodynamics
Topic overviewSpecific heat capacity and specific latent heatMeasuring specific heat capacity and calibrating a thermistorMeasuring specific latent heatInternal energy, temperature and absolute zeroMean kinetic energy and the absolute temperature scaleThe kinetic theory equation and its derivationThe ideal gas equation and molecular kinetic energyBoyle's law and investigating a fixed mass of gasBlack body radiation and Wien's lawThe Stefan-Boltzmann law and stellar calculations
Space
Nuclear Radiation
Topic overviewMass deficit, binding energy and the atomic mass unitBinding energy per nucleon, fission and fusionBackground radiation and the three types of nuclear radiationIonising power, penetration and changes in the nucleusNuclear equations and investigating gamma absorptionActivity, the decay constant and half-lifeDecay graphs and half-life calculations
Gravitational Fields
Oscillations
Topic overviewThe conditions for simple harmonic motionDisplacement, velocity and acceleration in simple harmonic motionThe mass-spring oscillator and the simple pendulumDisplacement, velocity and acceleration graphsReading period, amplitude and speed from oscillation graphsEnergy in an undamped oscillationDamping and where the energy goesFree and forced oscillations and resonanceResonance in practice and determining an unknown mass
Mechanics
- 17 subtopics
- 25 things to know
- Papers 1 and 3
What Mechanics covers
The core of Paper 1, drawn on again synoptically in Paper 3. Covers the equations of uniformly accelerated motion and the graphs that go with them, vectors and projectiles, Newton's three laws, momentum, moments and equilibrium, and work, energy and power.
Where it is assessed
Papers 1 and 3
Advanced Physics I, then the general and practical principles paper.
Check the Pearson Edexcel specification ↗The 17 subtopics
Each one has its own page.
- The equations of uniformly accelerated motionRecall questions on the four suvat equations, when they may be used, which to choose when time is not given, and the sign convention for vertical motion.Open →
- Displacement-time and velocity-time graphsRecall questions on what the gradients and areas of motion graphs represent, reading instantaneous velocity from a curve, and recognising non-uniform acceleration.Open →
- Scalars and vectorsRecall questions on the difference between a scalar and a vector, examples of each, and why distance and displacement, or speed and velocity, are not the same.Open →
- Resolving vectors and finding resultantsRecall questions on resolving a vector into perpendicular components, combining vectors at right angles and at any angle, and the forces on a body on a slope.Open →
- Projectile motionRecall questions on treating horizontal and vertical motion separately, what links them, the velocity at the highest point, and how air resistance changes the range.Open →
- Free-body diagrams and Newton's first and second lawsRecall questions on what belongs on a free-body diagram, the statements of the first and second laws, the definition of the newton, and applying F = ma.Open →
- Newton's third law, mass and weightRecall questions on what a third-law pair shares, why the pair never cancels, gravitational field strength, and the difference between mass and weight.Open →
- Terminal velocity and measuring g by free fallRecall questions on how a skydiver's acceleration changes, the shape of the velocity-time graph, and the electromagnet and light-gate determination of g.Open →
- Linear momentum and its conservationRecall questions on the definition and unit of momentum, why a direction must be fixed first, and how conservation follows from Newton's laws.Open →
- Elastic and inelastic collisions in one dimensionRecall questions on what separates an elastic from an inelastic collision, where the lost kinetic energy goes, and how momentum is still conserved when a ball rebounds.Open →
- The moment of a forceRecall questions on the definition and unit of a moment, why the perpendicular distance is used, and why a moment is not measured in joules.Open →
- Centre of gravity, equilibrium and the principle of momentsRecall questions on locating a centre of gravity, the two conditions for equilibrium, the principle of moments, and why a low, wide vehicle is stable.Open →
- Work done by a forceRecall questions on the definition of work and the joule, the cosine term when a force acts at an angle, and what negative work means.Open →
- Kinetic and gravitational potential energyRecall questions on the two energy equations, why doubling speed quadruples kinetic energy, and why the potential energy formula only holds near the Earth's surface.Open →
- Conservation of energy and dissipationRecall questions on the principle of conservation of energy, why a falling body's speed does not depend on its mass, and why dissipated energy cannot be recovered.Open →
- Power, and the equation P = FvRecall questions on the definition of power and the watt, the derivation of P = Fv, and the driving force needed at constant velocity.Open →
- Efficiency and wasted energyRecall questions on efficiency from energies and from powers, why it has no unit, why it can never reach 100%, and the joules in a kilowatt-hour.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Which equation of motion omits time, and what do the gradients of displacement-time and velocity-time graphs give?
Numbers
How are instantaneous velocity, average velocity and displacement read from motion graphs?
Numbers
What does a negative displacement-time gradient mean, and how is distance found when a velocity-time graph drops below the axis?
Key term
What is the difference between a scalar and a vector, and what are examples of each?
Key term
What is the difference between distance and displacement, and between speed and velocity?
Numbers
How is a vector resolved into two perpendicular components, and why is that useful?
Key term
What is true of three coplanar forces acting on a body in equilibrium when they are added tip to tail?
Key term
What quantity links the horizontal and vertical motions of a projectile?
Numbers
How is gravitational field strength defined, and is the normal contact force the third-law partner of an object's weight?
Evaluation
In the free-fall determination of g, why is a graph of height against t² plotted, and why is an electromagnet with electronic timing used?
Numbers
What is the difference between mass and weight, and why is N kg⁻¹ the same unit as m s⁻²?
Numbers
How does the acceleration of a skydiver change from the moment of jumping until terminal velocity is reached?
Key term
What should the length of each arrow on a free-body force diagram indicate?
Numbers
How is linear momentum defined and measured, and what does the principle of conservation of momentum state?
Process
How do the momentum changes of two colliding vehicles compare, and what distinguishes an elastic from an inelastic collision?
Numbers
What is the unit of a moment, why must the distance be perpendicular, and why is a moment not measured in joules?
Key term
How is the centre of gravity defined, when does it coincide with the centre of mass, and where does it lie on a uniform rod?
Numbers
How is the work done by a force calculated, including when the force acts at an angle to the motion?
Numbers
What is the equation for kinetic energy, what happens to it if speed doubles, and what does negative work mean?
Numbers
How is the change in gravitational potential energy calculated, and why does the path taken to a summit not matter?
Numbers
Why does a body falling freely through a height reach a speed given by the square root of 2gΔh?
Numbers
How are power and the watt defined, and how do two motors doing equal work in different times compare?
Numbers
How is efficiency calculated from energies and from powers?
Numbers
What is the difference between the power rating of an appliance and the energy it consumes?
Take Mechanics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Distance vs Displacement
Distance: total path length travelled. Displacement: straight-line change in position with direction.
Speed vs Velocity
Speed: rate of change of distance. Velocity: rate of change of displacement.
Mass vs Weight
Mass: measure of inertia. Weight: gravitational force acting on an object.
Questions from this topic
Each one with the model answer underneath.
- 1
Under what conditions may the equations of uniformly accelerated motion be used?
Model answer
They apply only when the acceleration is constant in both magnitude and direction and the motion is along a straight line.
- 2
State the equation of motion linking displacement, initial velocity, final velocity and time:
Model answer
The equation is s = (u + v)t/2.
- 3
State the equation of motion linking final velocity, initial velocity, acceleration and time:
Model answer
The equation is v = u + at.
- 4
State the equation of motion giving displacement in terms of initial velocity, acceleration and time:
Model answer
The equation is s = ut + ½at².
- 5
State the equation of motion that does not contain time:
Model answer
The equation is v² = u² + 2as.
- 6
Which equation of motion is most useful when time is neither given nor asked for?
Model answer
v² = u² + 2as, because it links the two velocities, the acceleration and the displacement without involving time.
What is inside Levo
Six ways to work the same material.
Mechanics revision questions
- What does Mechanics cover in Edexcel A-Level Physics?
- 17 subtopics: the equations of uniformly accelerated motion, displacement-time and velocity-time graphs, scalars and vectors, resolving vectors and finding resultants, projectile motion, free-body diagrams and newton's first and second laws, newton's third law, mass and weight, terminal velocity and measuring g by free fall, linear momentum and its conservation, elastic and inelastic collisions in one dimension, the moment of a force, centre of gravity, equilibrium and the principle of moments, work done by a force, kinetic and gravitational potential energy, conservation of energy and dissipation, power, and the equation p = fv and efficiency and wasted energy. Each one has its own page with questions and model answers.
- How is Mechanics organised?
- By the Edexcel 9PH0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Mechanics, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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