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
Linear Momentum and Impulse
Conservation of linear momentum
- 3 things to know
- Unit AS 1
Overview
Principle of conservation of linear momentum, isolated system in the context of momentum and how a rocket accelerates in terms of conservation of momentum.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Describe how the conservation of linear momentum is verified in a collision using trolleys and light gates.
Key term
Explain why the total momentum measured after a trolley collision is often slightly less than the total measured before.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the principle of conservation of linear momentum.
Model answer
The total momentum of a system of interacting bodies remains constant provided no resultant external force acts on that system.
- 2
What is meant by an isolated system in the context of momentum?
Model answer
An isolated system is one on which no resultant external force acts, so nothing outside it can change the total momentum of the bodies inside it.
- 3
Explain how the conservation of linear momentum follows from Newton's third law.
Model answer
During an interaction each body exerts an equal and opposite force on the other for exactly the same length of time, so the two impulses are equal and opposite, the two momentum changes are equal and opposite, and the total momentum is unchanged.
- 4
Explain why momentum must be treated as a vector when the principle is applied.
Model answer
Momenta directed opposite ways partly or wholly cancel, so the total must be found by attaching signs to the directions; adding the magnitudes alone would give a total that is far too large.
- 5
Does conservation of momentum still apply in a collision where kinetic energy is lost? Explain your answer.
Model answer
Yes; momentum is conserved in every interaction where no resultant external force acts, whatever happens to the kinetic energy, because the conservation follows from the equal and opposite forces of the impact and not from how energy is shared.
- 6
Explain how a rocket accelerates in terms of conservation of momentum.
Model answer
The rocket ejects burnt gas backwards, giving that gas momentum in one direction, so the rocket must gain an equal momentum in the opposite direction in order to keep the total momentum of the system constant.
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