Key term
CCEA A-Level Physics 1210
Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion
Linear Momentum and Impulse
Work, Energy and Power
Current, Charge and Potential Difference
Resistance and Resistivity
Topic overviewResistance and Ohm's lawOhmic and non-ohmic behaviourResistors in series and in parallelInvestigating current, voltage and resistance in series and parallel circuitsElectrical power and energy in resistive circuitsResistivity and the equation R = ρl/AMeasuring the resistivity of a metalCurrent–voltage characteristics of a conductor, a lamp and a diodeResistance, temperature and superconductivity
Internal Resistance and Potential Dividers
Topic overviewInternal resistance and terminal potential differenceConsequences of internal resistance for external circuitsMeasuring electromotive force and internal resistanceThe potential divider and variable outputPotential dividers in lighting and heating control circuitsLoaded potential dividers and output voltage calculations
Waves
Refraction
Lenses
Superposition, Interference and Diffraction
Topic overviewSuperposition of wavesStanding waves, nodes and antinodesStanding waves on stretched stringsStanding waves in a pipe closed at one endMeasuring the speed of sound with a resonance tubeConditions for observable interferencePath difference and phase differenceYoung's double slitDiffraction at a single slitThe diffraction grating
Quantum Physics
Wave-Particle Duality
Astronomy
Practical Skills and Data Analysis
Topic overviewChoosing and using measuring instrumentsPrecision, accuracy and recording measurementsUsing the cathode ray oscilloscope to measure voltage and frequencyTables, graphs and presenting resultsLinearising a relationship and using the gradientAbsolute and percentage uncertaintyCombining uncertainties and uncertainty on a graphRandom and systematic error, reliability and refining an experiment
Deformation of Solids
Thermal Physics
Topic overviewBoyle's law, Charles's law and the pressure lawThe ideal gas equation pV = nRTThe Avogadro constant, the mole and pV = NkTInternal energy and the distribution of molecular energyThe kinetic theory equation pV = ⅓Nm⟨c²⟩Average molecular kinetic energy and temperatureAbsolute zero and the kelvin scaleSpecific heat capacity and the electrical method
Uniform Circular Motion
Simple Harmonic Motion
Topic overviewDefining simple harmonic motion and a = −ω²xDisplacement, velocity and acceleration: x = A cos ωtThe simple pendulum and T = 2π√(l/g)The loaded spiral spring and T = 2π√(m/k)SHM graphs and finding velocity from a gradientFree vibrations, forced vibrations and resonanceDamping: light, critical and over-damping
The Nucleus and Radioactive Decay
Topic overviewAlpha-particle scattering and the nuclear atomNuclear radius and nucleon numberThe density of nuclear matterAlpha, beta and gamma radiation: nature, penetration and rangeNuclear equations and changes in nucleon and proton numberThe random and exponential nature of radioactive decayActivity, the decay constant and A = −λNExponential decay calculations with A = A₀e^(−λt)Half-life and measuring it
Nuclear Energy, Fission and Fusion
Gravitational Fields
Electric Fields
Capacitors
Magnetic Fields
Charged Particles and Accelerators
Uniform Circular Motion
Linear speed and angular velocity: v = rω
- 3 things to know
- Unit A2 1
Overview
Recall questions on v = rω with every symbol, its derivation from the definition of the radian, why the linear velocity is always changing in circular motion and the direction it points, the relation of ω to the period and the frequency, and worked calculations for points at different radii on a rotating body.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State the equation relating linear speed to angular velocity and define every symbol.
Key term
Show how v = rω follows from the definition of the radian.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the equation relating linear speed to angular velocity and define every symbol.
Model answer
v = rω, where v is the linear speed along the circular path in m s⁻¹, r the radius of the circle in metres and ω the angular velocity in rad s⁻¹.
- 2
Show how v = rω follows from the definition of the radian.
Model answer
An angle θ in radians subtends an arc of length s = rθ. Dividing both sides by the time taken gives s/t = r × θ/t, which is v = rω.
- 3
Why is the linear velocity of an object in uniform circular motion changing even though its speed is constant?
Model answer
Velocity is a vector, and although its magnitude stays the same its direction is continuously changing as the object moves round the circle.
- 4
In which direction does the linear velocity of an object in circular motion point at any instant?
Model answer
It points along the tangent to the circle at that point, at right angles to the radius.
- 5
A body moves in a circle of radius 0.50 m at 2.0 revolutions per second. Calculate its linear speed.
Model answer
ω = 2πf = 2π × 2.0 = 12.6 rad s⁻¹, so v = rω = 0.50 × 12.6 = 6.3 m s⁻¹.
- 6
A point on the rim of a wheel of radius 0.30 m moves at 4.5 m s⁻¹. Calculate the angular velocity of the wheel.
Model answer
ω = v/r = 4.5/0.30 = 15 rad s⁻¹.
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