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WJEC AS-Level Physics 1420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Solids Under Stress
Using Radiation to Investigate Stars
Particles and Nuclear Structure
Topic overviewQuarks, leptons and hadronsThe four interactions and conservation lawsThe first generation of quarks and leptonsAntiparticles and annihilationBaryons, antibaryons and mesonsDeducing quark compositions from chargeBeta decay and quark flavour changeTesting a reaction against the conservation rules
Conduction of Electricity
Resistance
Topic overviewCalculating resistance from resistivityPotential difference, Ohm's law and powerResistivity, temperature and superconductivityThe volt: energy transferred per unit chargeCurrent–voltage characteristics of non-ohmic componentsMeasuring resistance and resistivity in the laboratoryThe heating effect of a current and choosing a power equationThermistors and how a semiconductor's resistance falls with temperatureConductance, conductivity and comparing materials
D.C. Circuits
Topic overviewKirchhoff's laws, and resistors in series and parallelPotential dividers, emf and internal resistanceCells, resistivity, power and energyWorking out currents and potential differences in resistor networksSensor circuits with thermistors and LDRsInternal resistance, power transfer and short-circuit currentAmmeters, voltmeters and their effect on the circuit
The Nature of Waves
Wave Properties
Topic overviewEnergy transfer and the wave equationTransverse and longitudinal waves, path difference and intensityDiffraction and superpositionTwo-source interference and the diffraction gratingStationary wavesHow much a wave spreads at a gap or an obstacleCoherence and the conditions for observable interferenceYoung's double slit and λ = ay/DMeasuring wavelength with a diffraction gratingMeasuring the speed of sound with stationary waves
Refraction of Light
Photons
Topic overviewPhoton energy and the electronvoltThe photoelectric effectStopping potential and the Planck constantThe photoelectric effect and photon energiesLine spectra and energy levelsDemonstrating the photoelectric effectThe electromagnetic spectrum and typical photon energiesElectron diffraction and the de Broglie relationshipRadiation pressure
Lasers
Mathematical Requirements (Appendix C)
Topic overviewSignificant figures and arithmetic meansUncertainty and how uncertainties combineAlgebraic symbols and proportionalityRearranging and solving equationsSmall angle approximationsTangents and instantaneous rates of changeAreas under curves and numerical methodsReading a tangent on a motion graphStraight-line graphs and y = mx + cWhat a gradient and an intercept representLinearising a relationship to find a constantLog plots of exponential decayChoosing what to plot to find a constantLogarithmic scales and orders of magnitudeWorking with base-ten logarithmsThe shapes of common graphsInverse and root relationships on a graphAreas, volumes and PythagorasGeometry applied to physical situationsSubstituting into physical equationsTrigonometry and right-angled trianglesResolving a force into componentsRadians, arc length and force diagramsRandom processes and translating between representationsMean values and periodic functionsSymbols for approximation and comparison
Dynamics
- 6 subtopics
- 18 things to know
- AS Unit 1
What Dynamics covers
Dynamics is examined on AS Unit 1 of WJEC Physics, Motion, Energy and Matter. 84 recall questions across 6 subtopics.
The 6 subtopics
Each one has its own page. WJEC AS Physics students sit this topic in the first year.
- Newton's second law and momentumRecall questions on Newton's second law and momentum.Open →
- Force and Newton's lawsRecall questions on Force and Newton's laws.Open →
- Impulse and the force–time graphRecall questions on Impulse and the force–time graph.Open →
- Collisions and explosions in one dimensionRecall questions on Collisions and explosions in one dimension.Open →
- Free body diagrams and connected bodiesRecall questions on Free body diagrams and connected bodies.Open →
- Newton's third law pairs and everyday forcesRecall questions on Newton's third law pairs and everyday forces.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
How does Newton's second law relate force to momentum?
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Why must a positive direction be chosen before any one-dimensional collision problem is solved?
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Why does a passenger in a lift whose cable has broken feel weightless?
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State the relationship between resultant force, mass and acceleration for a body of constant mass.
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What is a force?
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Define the impulse of a force.
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State the equation relating impulse to momentum and define each symbol with its unit.
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Besides momentum, what quantity is conserved in a perfectly elastic collision?
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What forces belong on a free body diagram of an object, and what must be left off?
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Identify the Newton's third law pair involved when a swimmer pushes water backwards.
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A rocket engine fires in the vacuum of space. Explain what pushes the rocket forward.
Numbers
Calculate the acceleration of a 1200 kg car acted on by a resultant force of 3600 N.
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Identify the Newton's third law partner to the Earth's gravitational pull on a book.
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In which direction does the impulse delivered to a body act?
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A 4.0 kg rifle fires a 0.020 kg bullet at 350 m s⁻¹. Calculate the recoil velocity of the rifle.
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Why is the string in a connected-body problem usually taken to be light and inextensible?
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When a car accelerates along a road, what force pushes it forwards and what is that force's third law partner?
Take Dynamics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
An elastic collision vs An inelastic collision
An elastic collision: one in which the total kinetic energy is unchanged. An inelastic collision: one in which some kinetic energy is transferred to other forms.
Questions from this topic
Each one with the model answer underneath.
- 1
State the relationship between resultant force, mass and acceleration for a body of constant mass.
Model answer
F = ma, where F is the resultant force, m is the mass and a is the acceleration.
- 2
Calculate the acceleration of a 1200 kg car acted on by a resultant force of 3600 N.
Model answer
a = F/m = 3600 ÷ 1200 = 3.0 m s⁻².
- 3
What resultant force is needed to accelerate a 0.15 kg ball at 40 m s⁻²?
Model answer
F = ma = 0.15 × 40 = 6.0 N.
- 4
Define linear momentum.
Model answer
Linear momentum is the product of the mass of a body and its velocity, p = mv.
- 5
What is the SI unit of momentum?
Model answer
kg m s⁻¹, which is equivalent to N s.
- 6
Is momentum a scalar or a vector? Explain.
Model answer
A vector, because velocity is a vector, so momentum has the same direction as the velocity.
What is inside Levo
Six ways to work the same material.
Dynamics revision questions
- Is Dynamics examined at AS in WJEC Physics?
- Yes. It sits in AS Unit 1, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Dynamics cover in WJEC AS-Level Physics?
- 6 subtopics: newton's second law and momentum, force and newton's laws, impulse and the force–time graph, collisions and explosions in one dimension, free body diagrams and connected bodies and newton's third law pairs and everyday forces. Each one has its own page with questions and model answers.
- How is Dynamics organised?
- By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Dynamics, 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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