Materials is a core part of A-Level Physics. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Densityρ = m/V, mass per unit volume of a substance, measured in kg m⁻³.
Hooke's lawF = kx for an elastic material below the limit of proportionality.
Young's modulusE = stress/strain, a measure of stiffness, measured in pascals.
Stressσ = F/A, force per unit cross-sectional area, in pascals.
Strainε = ΔL/L, fractional change in length; dimensionless.
Elastic limitMaximum stress beyond which a material does not return to its original length when load is removed.
Stress & strainStress = force/area; strain = extension/length.
Young modulusStress ÷ strain; a measure of stiffness.
Specific heat capacityEnergy to raise 1 kg of a substance by 1 °C.
Internal energyTotal kinetic and potential energy of particles; linked to temperature.
Ideal gas lawspV relationships linking pressure, volume and temperature.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What does Young's modulus measure?✗ Young's modulus measures how strong a material is — how much force it can take before breaking. ✓ The stiffness of a material — the ratio of stress to strain in the elastic region.
What is the formula for Young's modulus?✗ Force / area — the same as stress itself. ✓ Stress / strain — the ratio in the linear (elastic) region of a stress-strain graph.
What happens to a metal wire stretched beyond its elastic limit?✗ It snaps immediately at the elastic limit. ✓ It deforms plastically and will not return to its original length when the load is removed.
What is the difference between heat and temperature?✗ Heat and temperature are the same thing — both measure how hot something is. ✓ Heat is the energy transferred due to temperature difference; temperature measures average kinetic energy of particles.
Why does a metal spoon in hot water heat up faster than a wooden one?✗ Metal heats up faster because it has a lower specific heat capacity, requiring less energy per degree. ✓ Metals have higher thermal conductivity, so heat is transferred more rapidly through them.
Practise Materials — free games
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