Numbers
OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Topic overviewAnalogue and digital measuring instrumentsImproving accuracy with repeat timing, fiducial markers and plumb linesTiming, calipers and micrometersConstructing and testing circuitsSignal generators and oscilloscopesGenerating and measuring wavesData loggers, modelling software and ionising radiation
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Topic overviewProgressive waves and their propertiesThe wave equationReflection, refraction and diffractionWave graphs and intensityThe electromagnetic spectrumPolarisationRefraction and refractive indexCritical angle and total internal reflectionThe principle of superpositionInterference, coherence and path differenceTwo-source interference, Young's double-slit experiment and the diffraction gratingForming stationary wavesStationary waves on strings and in air columnsMeasuring the speed of soundNode spacing, amplitude and phase in stationary wavesHarmonics and the fundamental mode
Quantum Physics
Thermal Physics
Topic overviewThermal equilibrium and absolute temperatureThe kinetic model of solids, liquids and gasesBrownian motion and internal energySpecific heat capacityMeasuring specific heat capacitySpecific latent heatMeasuring specific latent heatMoles, the Avogadro constant and kinetic theoryGas laws, the ideal gas equation and r.m.s. speedMaxwell-Boltzmann distribution, Boltzmann constant and internal energy
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Topic overviewThe solar system and the birth of a starThe death of a low-mass starSupernovae, neutron stars and black holesThe Hertzsprung-Russell diagramEnergy levels and emission spectraAbsorption spectra and spectral linesPhoton energy and the diffraction gratingWien's law and Stefan's lawAstronomical distances, parallax and the cosmological principleDoppler shift and Hubble's lawThe expanding universe and the Big BangEvidence for the Big Bang and dark energy
Capacitors
Topic overviewCapacitance and charging a capacitorCapacitors in seriesCapacitors in parallel and combined circuitsEnergy stored by a capacitorCharging and discharging through a resistorInvestigating capacitor dischargeThe time constantIterative modelling, exponential decay and the constant-ratio property
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Topic overviewAlpha-particle scattering and the nuclear modelProton number, nucleon number and isotopesThe strong nuclear force and nuclear radiusParticles, antiparticles and hadronsLeptons and the quark modelQuark composition and chargesBeta decay in the quark modelRadioactive decay and the three radiationsNuclear decay equationsActivity, decay constant and half-lifeExponential decay and radioactive datingMass-energy equivalenceAnnihilation, mass defect and binding energyBinding energy per nucleon and induced fissionThe fission reactor and nuclear wasteNuclear fusion and balancing nuclear equations
Forces in Action
- 5 subtopics
- 15 things to know
- Papers 1 and 3
What Forces in Action covers
Newton's second law in use, drag and terminal velocity, moments and equilibrium, and the pressure and upthrust a fluid exerts.
Where it is assessed
Papers 1 and 3
Forces and motion, examined on Modelling Physics and Unified Physics.
Check the OCR specification ↗The 5 subtopics
Each one has its own page.
- Newton's second law and weightRecall questions on Newton's second law and F = ma, the newton, weight and its calculation, tension, normal contact force and friction, and analysing motion under a constant force in one and two dimensions.Open →
- Drag and the factors affecting itRecall questions on drag and how speed, cross-sectional area, shape and fluid density affect it, and how drag changes the net force and acceleration of a falling object.Open →
- Terminal velocityRecall questions on defining terminal velocity, the initial acceleration of a falling object, and determining terminal velocity experimentally in a viscous liquid and with paper cones in air.Open →
- Moments, couples and equilibriumRecall questions on free-body diagrams, moments and the principle of moments, couples and torque, centre of mass and centre of gravity, finding the centre of gravity of a lamina, and the conditions for equilibrium.Open →
- Density, pressure and upthrustRecall questions on density and pressure with their calculations, pressure at a depth p = hρg, why pressure increases with depth, how the pressure difference produces upthrust, and Archimedes' principle.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Define pressure, state its equation, and state to what states of matter the definition applies.
Key term
In a viscous liquid experiment, how is terminal velocity identified and then calculated?
Numbers
State the equation for pressure at a depth in a fluid, explain why pressure increases with depth, and explain why the bottom surface of a submerged object is at greater pressure than the top.
Numbers
Define density and write its equation, identifying each term.
Process
What happens to the drag force on a falling object as its speed increases?
Numbers
Write the equation for the torque of a couple.
Key term
When finding the centre of gravity of an irregular lamina, what is done first?
Key term
Explain how the pressure difference between the top and bottom of a submerged object produces upthrust.
Key term
Define drag.
Key term
State Newton's second law of motion.
Key term
How does the speed of an object affect the drag force it experiences when travelling through air?
Numbers
Calculate the weight when mass = 691.8 kg, gravitational field strength = 9.81 N kg⁻¹.
Numbers
Calculate the moment when force = 354 N, perpendicular distance = 1.15 m.
Key term
Define upthrust.
Take Forces in Action further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Moment of a force vs Torque of a couple
Moment of a force: force multiplied by the perpendicular distance from the pivot. Torque of a couple: one force of the pair multiplied by the perpendicular separation between them.
Centre of mass vs Centre of gravity
Centre of mass: the point at which all the matter of a body may be taken to act. Centre of gravity: the point at which the whole weight of a body may be taken to act.
Density vs Pressure
Density: mass per unit volume. Pressure: force per unit area acting normally to a surface.
Questions from this topic
Each one with the model answer underneath.
- 1
State Newton's second law of motion.
Model answer
The net force acting on an object equals its mass multiplied by its acceleration.
- 2
Write the equation that expresses Newton's second law.
Model answer
F = ma
- 3
Calculate the net force when mass = 69.2 kg, acceleration = 13.9 m s⁻².
Model answer
Net force = 69.2 × 13.9 = 962 N.
- 4
Define the newton as the SI unit of force.
Model answer
The newton is the force required to accelerate a mass of one kilogram at one metre per second squared.
- 5
What is the weight of an object?
Model answer
The weight of an object is the gravitational force acting on it.
- 6
State the equation used to calculate the weight of an object.
Model answer
W = mg, where W is weight, m is mass, and g is gravitational field strength.
What is inside Levo
Six ways to work the same material.
Forces in Action revision questions
- What does Forces in Action cover in OCR A-Level Physics A?
- 5 subtopics: newton's second law and weight, drag and the factors affecting it, terminal velocity, moments, couples and equilibrium and density, pressure and upthrust. Each one has its own page with questions and model answers.
- How is Forces in Action organised?
- By the OCR H556 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Forces in Action, 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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