Key term
Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Topic overviewScalar and vector quantitiesExamples of vectors and scalars, and velocitySpeed, distance, time and distance-time graphsAcceleration and the equation v squared minus u squaredVelocity-time graphs and free fallMeasuring speed in the laboratory, and typical everyday speedsNewton's first law, and investigating force, mass and accelerationNewton's second and third lawsWeight, mass and gravitational field strengthReaction time, stopping distance and large decelerationsFactors affecting stopping distance and reaction timeBraking distance, speed and work done
Conservation of Energy
Waves
Topic overviewWhat waves transfer, and the evidence for itFrequency, wavelength, amplitude and periodLongitudinal and transverse wavesThe wave equationMeasuring wave speed, and what happens at a boundaryMeasuring waves in ripple tanks, strings and solidsReflection, refraction, transmission and absorption at a boundary
Light and the Electromagnetic Spectrum
Topic overviewReflection, refraction and total internal reflectionWhy objects appear colouredLenses, ray diagrams and imagesProperties of electromagnetic wavesInvestigating refraction in glass blocksThe groups of the electromagnetic spectrumThe continuous spectrum, and what our eyes can detectEmitting and absorbing thermal radiationHow radiation is generated, and why danger rises with frequencyHarmful effects of excessive exposure to radiationUses of electromagnetic radiation
Radioactivity
Topic overviewThe atom and the size of atomsIsotopes, atomic number and mass numberRelative masses and charges of subatomic particlesElectron orbits and energy levelsForming ions, and how the atomic model changedTypes of ionising radiationBackground radiation and detecting radioactivityAlpha, beta and gamma, and their penetrating powerBeta-minus and beta-plus decayEffects of decay on atomic number and mass numberBalancing nuclear equationsActivity and the becquerelHalf-life and the randomness of decayHalf-life calculationsUses of radioactivity, and how danger depends on half-lifeThe dangers of ionising radiationSafety precautions, contamination and irradiationRadiotherapy, medical tracers and PET scannersNuclear power and where nuclear energy comes fromFission of uranium-235 and the chain reactionControlling a reactor and generating electricityNuclear fusion and how it differs from fissionWhy fusion needs extreme conditions
Astronomy
Topic overviewWeight and gravitational field strength on other bodiesThe Solar System and the order of the planetsHow ideas about the Solar System and ways of observing it have changedOrbits of moons, planets, comets and satellitesGravity, orbital speed and stable orbitsThe Steady State and Big Bang theoriesEvidence for an expanding UniverseThe Doppler effect and red-shift in galaxiesThe life cycle of a star like the SunThe life cycle of stars more massive than the Sun
Energy – Forces Doing Work
Topic overviewEnergy stores and energy transfer diagramsChanging a system's energy, and measuring work doneWork done and the energy changes it causesGravitational potential and kinetic energy calculationsDissipation and wasted energyPower as the rate of energy transferThe watt, and calculating efficiency
Forces and Their Effects
Electricity and Circuits
Topic overviewThe atom, and drawing circuit diagramsSeries and parallel circuitsPotential difference and the voltmeterEnergy transferred by moving chargeCurrent, charge and measuring currentResistance and the equation V = IRResistors in series and in parallelDesigning circuits to test componentsInvestigating resistance in circuitsCurrent-potential difference graphs for componentsLight-dependent resistors and thermistorsThe heating effect of an electric currentUses of the heating effect, and the equation E = IVtPower as energy transferred per secondCalculating electrical powerEnergy transfer in domestic devices, and power ratingsDirect and alternating currentAlternating current and the UK mains supplyLive and neutral wires, earthing and fusesFuses in the live wire, mains voltages and electrical dangers
Static Electricity
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Topic overviewKinetic theory and differences in densityCalculating density, and investigating itChanges of state and internal energySpecific heat capacitySpecific latent heat and thermal insulationInvestigating the specific heat capacity of waterGas pressure and the motion of particlesAbsolute zero and the kelvin scaleCompressing gases, and the force a gas exertsPressure and volume of a fixed mass of gas
Forces and Matter
Atmospheric pressure and pressure in a fluid
- 3 things to know
- Paper 2
Overview
Why atmospheric pressure and density fall with height, pressurised aircraft cabins and the atmosphere's lack of an edge, and total pressure in a fluid as liquid pressure plus atmospheric pressure in lakes, pools and the sea.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain why the cabin of an aircraft is pressurised when it flies at high altitude.
Key term
Explain why the atmosphere has no sharp upper edge.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Explain why atmospheric pressure falls as height above the ground increases.
Model answer
There is less air above, so a smaller weight of air presses down on each square metre.
- 2
Describe how the density of the atmosphere changes with height above the ground.
Model answer
It decreases, because the air particles become more spread out higher up.
- 3
Explain why the atmosphere is denser near the ground than high above it.
Model answer
The weight of all the air above squashes the lower air, packing its particles closer together.
- 4
Explain why the cabin of an aircraft is pressurised when it flies at high altitude.
Model answer
Atmospheric pressure outside is very low there, so the cabin must be held at a higher pressure for people to breathe comfortably.
- 5
Explain why the atmosphere has no sharp upper edge.
Model answer
The air simply thins out gradually with height until almost no particles remain.
- 6
State the two contributions that make up the total pressure at a point below the surface of a lake.
Model answer
The pressure due to the water above the point, plus atmospheric pressure pushing down on the surface.
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