What does the CCEA AS 1 Forces, Energy and Electricity unit cover?

AS 1 is the mechanics and electricity foundation of the course. It covers physical quantities and SI units with uncertainties, scalars and vectors and resolving forces, forces and equilibrium including moments and couples, dynamics with the equations of motion, Newton's laws and momentum, work, energy and power and the conservation of energy, electric charge, current, potential difference, resistance and resistivity, and DC circuits with Kirchhoff's laws, e.m.f., internal resistance and the potential divider.

Which equations must I recall for AS 1?

Know the four equations of motion for uniform acceleration, Newton's second law as force equals rate of change of momentum, momentum as mass times velocity and impulse as force times time, work done as force times distance, kinetic energy and gravitational potential energy, power as work over time, and the electrical relations for current, potential difference, resistance, resistivity, series and parallel resistors, the terminal voltage equation and the potential divider. A data and formula sheet is provided, but you should be fluent in rearranging and using all of them.

What is the difference between elastic and inelastic collisions?

In both kinds of collision the total momentum is conserved, provided no external resultant force acts. In an elastic collision the total kinetic energy is also conserved. In an inelastic collision momentum is conserved but some kinetic energy is transferred to other forms such as heat and sound, which is what happens when objects stick together.

What is the most common mistake in AS 1?

In mechanics, the frequent error is using the equations of motion when the acceleration is not constant, or treating Newton's third-law pair as acting on the same body. In electricity, the common slips are adding parallel resistors directly instead of adding their reciprocals, and forgetting internal resistance so the terminal voltage is taken to equal the e.m.f.

How should I revise the AS 1 unit?

Work topic by topic against the specification statements. Learn each definition and the conditions on every equation, then drill calculations carrying SI units through. Practise resolving vectors, applying the principle of moments, momentum conservation problems, energy and efficiency calculations, and circuit problems with Kirchhoff's laws and internal resistance. Draw and interpret the current-voltage characteristics of a resistor, a filament lamp and a diode, because they are tested directly.

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CCEA A-Level Physics AS 1 Forces, Energy and Electricity: a complete overview of mechanics, energy and DC circuits

A deep-dive CCEA A-Level Physics guide to the AS 1 Forces, Energy and Electricity unit. Covers physical quantities and units, scalars and vectors, forces and equilibrium, dynamics and Newton's laws, work, energy and power, electric charge, current and resistance, and DC circuits, with the definitions and equations CCEA examines.

Generated by Claude Opus 4.818 min readCCEAUpdated 2026-06-02

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Jump to a section

What this unit demands
Physical quantities, scalars and vectors
Forces, equilibrium and dynamics
Work, energy and power
Electricity and DC circuits
How this unit is examined
Check your knowledge

What this unit demands

AS 1 Forces, Energy and Electricity is the foundation of CCEA A-Level Physics. It establishes the language of measurement, the mechanics of forces and motion, the conservation laws for momentum and energy, and the behaviour of DC circuits. The examiners test two linked skills: precise recall of definitions, laws and conditions, and confident calculation that carries SI units through correctly.

This guide walks through the seven 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.

Physical quantities, scalars and vectors

Every measurement is a number times a unit built from the seven SI base units. Equations must be homogeneous, and uncertainties are quoted as absolute, fractional or percentage values, with percentage uncertainties added for products and quotients. A scalar has magnitude only and a vector has magnitude and direction; vectors add tip to tail and resolve into perpendicular components $F\cos\theta$ and $F\sin\theta$ .

Forces, equilibrium and dynamics

The moment of a force is force times perpendicular distance, and the principle of moments balances clockwise against anticlockwise moments. A body is in equilibrium when the resultant force and the resultant moment are both zero. The equations of motion describe uniform acceleration, Newton's laws relate force to the rate of change of momentum, and momentum is conserved in collisions and explosions when no external resultant force acts.

Work, energy and power

Work done is force times distance in the direction of the force, transferring energy between the kinetic store $\tfrac{1}{2}mv^2$ and the gravitational store $mgh$ . Energy is conserved, only transferred between stores. Power is the rate of energy transfer, and efficiency is the useful output divided by the total input, always less than one because some energy is dissipated.

Electricity and DC circuits

Current is the rate of flow of charge and potential difference is energy per unit charge. Resistance is voltage over current, Ohm's law holds for a metal at constant temperature, and resistivity links resistance to a sample's dimensions. Kirchhoff's laws apply charge and energy conservation to circuits, real sources have internal resistance giving lost volts, and a potential divider splits a voltage in the ratio of the resistances.

How this unit is examined

A typical CCEA profile for AS 1:

Definitions and laws. Stating Newton's laws, the principle of moments, Ohm's law and Kirchhoff's laws precisely.
Calculation. Equations of motion, momentum and impulse, energy and efficiency, and circuit problems with internal resistance.
Graphs. Reading velocity-time graphs and the current-voltage characteristics of a resistor, a filament lamp and a diode.
Application. Resolving forces on a slope, projectile motion, and sensor circuits using a potential divider.

Check your knowledge

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

State two conditions for a body to be in equilibrium. (2 marks)
A car accelerates uniformly from rest to $20\,\text{m}\,\text{s}^{-1}$ in $8.0\,\text{s}$ . Find its acceleration and the distance travelled. (3 marks)
State Newton's second law in terms of momentum. (1 mark)
Two trolleys of mass $2.0\,\text{kg}$ and $3.0\,\text{kg}$ approach at $4.0\,\text{m}\,\text{s}^{-1}$ and $1.0\,\text{m}\,\text{s}^{-1}$ in opposite directions and stick together. Find their common velocity. (3 marks)
Define power and state its unit. (2 marks)
Distinguish between resistance and resistivity. (2 marks)
State Kirchhoff's two laws and the conservation principle behind each. (2 marks)
A cell of e.m.f. $6.0\,\text{V}$ and internal resistance $0.5\,\Omega$ drives a current of $2.0\,\text{A}$ . Find the terminal potential difference. (2 marks)

Solutions

Q1: The resultant force in any direction is zero, and the resultant moment about any point is zero.
Q2: $a = \frac{20}{8.0} = 2.5\,\text{m}\,\text{s}^{-2}$ ; distance $s = \tfrac{1}{2}(u + v)t = \tfrac{1}{2}(0 + 20)(8.0) = 80\,\text{m}$ .
Q3: The resultant force equals the rate of change of momentum.
Q4: Taking the first trolley as positive: $2.0(4.0) + 3.0(-1.0) = (2.0 + 3.0)v$ , so $5.0 = 5.0v$ and $v = 1.0\,\text{m}\,\text{s}^{-1}$ in the direction of the first trolley.
Q5: Power is the rate of transferring energy (or doing work), measured in watts ( $\text{W}$ ), where $1\,\text{W} = 1\,\text{J}\,\text{s}^{-1}$ .
Q6: Resistance depends on the dimensions of a particular sample; resistivity is a property of the material itself, measured in $\Omega\,\text{m}$ , and links resistance to length and area through $R = \frac{\rho L}{A}$ .
Q7: First law: total current into a junction equals total current out (conservation of charge). Second law: round any loop, the sum of e.m.f.s equals the sum of potential drops (conservation of energy).
Q8: $V = \varepsilon - Ir = 6.0 - (2.0 \times 0.5) = 5.0\,\text{V}$ .

Sources & how we know this

CCEA GCE Physics specification — CCEA (2016)