What does the CCEA A2 1 unit cover?

A2 1 covers the response of matter to forces and energy and the mathematics of motion and fields. It includes deformation of solids with Hooke's law, stress, strain, the Young modulus and strain energy, thermal physics with internal energy, specific heat capacity, latent heat, the ideal gas equation and kinetic theory, circular motion with angular velocity, centripetal acceleration and force, simple harmonic motion with its defining condition, energy, damping and resonance, and gravitational fields with Newton's law, field strength, potential, satellite orbits and Kepler's third law.

What is the defining condition for simple harmonic motion?

A body moves with simple harmonic motion when its acceleration is directly proportional to its displacement from equilibrium and is always directed back towards equilibrium, written as a equals minus omega squared x. This defining condition gives sinusoidal displacement, a period that is independent of amplitude, maximum speed at the centre, and a constant exchange between kinetic and potential energy.

Why is gravitational potential always negative?

Gravitational potential is the work done per unit mass to bring a small mass from infinity to a point in the field. Because gravity is attractive, the field does work as the mass moves inward, so the potential is taken as zero at infinity and becomes more negative closer to the mass. This is why every value of gravitational potential within a field is negative.

What is the most common mistake in A2 1?

Common errors include using degrees Celsius rather than kelvin in the ideal gas equation, treating the centripetal force as an outward force, dropping the minus sign in the simple harmonic motion condition, and forgetting that gravitational potential is negative or that r is measured from the centre of a planet. Carrying SI units and the correct signs through every calculation avoids most of these.

How should I revise the A2 1 unit?

Work topic by topic against the specification statements. Drill the Young modulus and strain-energy calculations and read stress-strain graphs, practise heat capacity, latent heat and ideal gas problems and state the kinetic-theory link, and rehearse centripetal force, simple harmonic motion and gravitation calculations. Learn the defining conditions and the equations precisely, and practise the derivations such as Kepler's third law that CCEA can ask you to set out.

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CCEA A-Level Physics A2 1 Deformation, Thermal Physics, Circular Motion, SHM and Gravity: a complete overview

A deep-dive CCEA A-Level Physics guide to the A2 1 unit on deformation of solids, thermal physics and ideal gases, circular motion, simple harmonic motion and gravitational fields. Covers Hooke's law and the Young modulus, heat capacity and kinetic theory, centripetal force, the SHM equations and resonance, and Newton's law of gravitation, with the equations CCEA examines.

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Jump to a section

What this unit demands
Deformation of solids
Thermal physics and ideal gases
Circular motion and SHM
Gravitational fields
How this unit is examined
Check your knowledge

What this unit demands

A2 1 brings together the response of materials to forces, the behaviour of gases and heat, and the mathematics of rotation, oscillation and gravity. The examiners test precise definitions and defining conditions, confident calculation across several equations, and the ability to set out short derivations such as the mean kinetic energy of a gas molecule and Kepler's third law.

This guide walks through the five dot points of the unit, then sets out the exam patterns CCEA repeats. Each topic has a matching dot-point page with practice questions; this overview ties them together.

Deformation of solids

Hooke's law gives $F = kx$ up to the limit of proportionality. Stress is force per area and strain is extension per original length; their ratio is the Young modulus, a property of the material. The strain energy stored is the area under the force-extension graph, $\tfrac{1}{2}Fx$ , and stress-strain graphs distinguish brittle from ductile materials.

Thermal physics and ideal gases

Internal energy is the total random energy of the molecules and temperature measures their average kinetic energy. Specific heat capacity and specific latent heat quantify heating and changes of state. The ideal gas equation $pV = nRT$ and kinetic theory combine to show the mean kinetic energy of a molecule is $\tfrac{3}{2}kT$ .

Circular motion and SHM

Circular motion has a centripetal acceleration $\frac{v^2}{r}$ towards the centre, produced by a centripetal force that is whatever real force points inward. Simple harmonic motion is defined by $a = -\omega^2 x$ , giving a period independent of amplitude, energy that swaps between kinetic and potential, and resonance when the driving frequency matches the natural frequency.

Gravitational fields

Newton's law of gravitation gives $F = \frac{GMm}{r^2}$ . The field strength $g = \frac{GM}{r^2}$ follows an inverse-square law, and the potential $V = -\frac{GM}{r}$ is always negative. For satellites, gravity provides the centripetal force, giving Kepler's third law $T^2 \propto r^3$ , and a geostationary orbit has a 24-hour period over the equator.

How this unit is examined

A typical CCEA profile for A2 1:

Definitions and conditions. Hooke's law, the SHM condition, field strength and potential.
Calculation. The Young modulus, heat capacity and gas problems, centripetal force, SHM speeds and gravitation.
Graphs. Stress-strain curves, displacement-time graphs and resonance curves.
Derivation. The mean kinetic energy of a gas molecule and Kepler's third law.

Check your knowledge

A mix of recall and calculation questions covering the unit. Attempt them under timed conditions, then check against the solutions.

Define the Young modulus and give its unit. (2 marks)
A spring of spring constant $150\,\text{N}\,\text{m}^{-1}$ is stretched by $0.20\,\text{m}$ . Find the energy stored. (2 marks)
How much energy is needed to melt $0.30\,\text{kg}$ of ice? Take $L = 3.3 \times 10^{5}\,\text{J}\,\text{kg}^{-1}$ . (2 marks)
State what the absolute temperature of a gas measures, according to kinetic theory. (1 mark)
A car of mass $900\,\text{kg}$ takes a bend of radius $30\,\text{m}$ at $15\,\text{m}\,\text{s}^{-1}$ . Find the centripetal force. (2 marks)
State the defining condition for simple harmonic motion. (2 marks)
State the condition for resonance and what happens to the amplitude at resonance. (2 marks)
State Newton's law of gravitation in words. (2 marks)

Solutions

Q1: The Young modulus is the ratio of tensile stress to tensile strain in the elastic region, $E = \frac{\sigma}{\varepsilon}$ , measured in pascals ( $\text{Pa}$ ).
Q2: $E = \tfrac{1}{2}kx^2 = \tfrac{1}{2}(150)(0.20)^2 = 3.0\,\text{J}$ .
Q3: $Q = mL = 0.30 \times 3.3 \times 10^{5} = 9.9 \times 10^{4}\,\text{J}$ .
Q4: The mean (translational) kinetic energy of its molecules.
Q5: $F = \frac{mv^2}{r} = \frac{900 \times 15^2}{30} = 6750\,\text{N}$ , provided by friction.
Q6: The acceleration is directly proportional to the displacement from equilibrium and is always directed towards equilibrium, $a = -\omega^2 x$ .
Q7: Resonance occurs when the driving frequency equals the natural frequency; the amplitude then reaches a maximum.
Q8: Two point masses attract each other with a force proportional to the product of their masses and inversely proportional to the square of their separation.

Sources & how we know this

CCEA GCE Physics specification — CCEA (2016)