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
Newton's Laws of Motion
Newton's second law and F = ma
- 3 things to know
- Unit AS 1
Overview
Recall questions on the statement of the second law and the equation with its units, the definition of the newton, why it is the resultant force that matters, how W = mg follows, why mass is fixed but weight is not, and worked problems on a car, a struck ball, a parachutist and uniform braking.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain how the equation W = mg follows from Newton's second law.
Numbers
A car of mass 800 kg has a driving force of 2400 N and experiences 900 N of resistance. Calculate its acceleration.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State Newton's second law of motion for a body of constant mass.
Model answer
The acceleration of a body of constant mass is directly proportional to the resultant force acting on it and takes place in the direction of that force.
- 2
State the equation F = ma, defining each symbol with its unit and stating the condition under which it applies.
Model answer
The equation is F = ma, where F is the resultant force in newtons (N), m is the mass in kilograms (kg) and a is the acceleration in metres per second squared (m s⁻²); it applies when the mass of the body is constant.
- 3
Define the newton.
Model answer
One newton is the resultant force that gives a mass of one kilogram an acceleration of one metre per second squared.
- 4
State the relationship between the direction of the resultant force and the direction of the acceleration.
Model answer
The acceleration is always in the same direction as the resultant force, whatever direction the body happens to be moving in at the time.
- 5
Explain how the equation W = mg follows from Newton's second law.
Model answer
A body falling freely has only its weight acting on it and accelerates at g, so putting F = W and a = g into F = ma gives W = mg, where W is the weight in newtons, m the mass in kilograms and g the acceleration of free fall in m s⁻².
- 6
Explain why the mass of an object is the same everywhere but its weight is not.
Model answer
Mass is the quantity of matter in the object and does not depend on location, whereas weight is mg and so changes wherever the gravitational field strength g differs, such as on the Moon.
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