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
Impulse and the impulse–momentum equation
- 3 things to know
- Unit AS 1
Overview
Impulse–momentum equation, defining each symbol and its unit, words what the impulse–momentum equation says and what the sign of an impulse tells you.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State the unit of impulse and show that it is the same as the unit of momentum.
Key term
State in words what the impulse–momentum equation says.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define impulse.
Model answer
Impulse is the product of a force and the time for which that force acts, F × t, and it is a vector in the direction of the force.
- 2
State the unit of impulse and show that it is the same as the unit of momentum.
Model answer
The unit is the newton second (N s); since 1 N = 1 kg m s⁻², one newton second is 1 kg m s⁻¹, which is the unit of momentum.
- 3
State the impulse–momentum equation, defining each symbol and its unit.
Model answer
The equation is Ft = mv − mu, where F is the constant resultant force in newtons, t the time for which it acts in seconds, m the mass in kilograms, u the initial velocity and v the final velocity in m s⁻¹.
- 4
State in words what the impulse–momentum equation says.
Model answer
The impulse of the resultant force acting on a body is equal to the change in the momentum of that body.
- 5
Show how Ft = mv − mu follows from F = ma.
Model answer
For uniform acceleration a = (v − u)/t, so substituting into F = ma gives F = m(v − u)/t, and multiplying both sides by t gives Ft = mv − mu.
- 6
How is the impulse found when the force acting is not constant?
Model answer
The impulse is the area between the force–time graph and the time axis, which is equivalent to using the average force multiplied by the total contact time.
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