This GCSE Physics equations guide gives you a reusable formula sheet for AQA, Edexcel and OCR study, with symbols, units, rearrangement methods, worked examples and a practical checklist for checking your answer before moving on.
Overview
Equations are not a separate topic to memorise once and forget. They are tools for describing relationships between physical quantities. Strong GCSE Physics revision means knowing what each symbol represents, choosing suitable units, substituting values carefully and explaining whether the result is sensible.
The exact equations printed on an exam paper or supplied in a formula sheet can depend on the qualification, tier, paper and assessment arrangements. AQA, Edexcel and OCR specifications also differ in how topics and required relationships are presented. Use the list below as a revision reference, but compare it with your own specification and the formula sheet provided by your school or exam board.
Core GCSE Physics equations
| Relationship | Equation | Typical SI units |
|---|---|---|
| Speed | speed = distance ÷ time | m/s, m, s |
| Acceleration | acceleration = change in velocity ÷ time | m/s², m/s, s |
| Density | density = mass ÷ volume | kg/m³, kg, m³ |
| Weight | weight = mass × gravitational field strength | N, kg, N/kg |
| Force and extension | force = spring constant × extension | N, N/m, m |
| Moment | moment = force × distance | N m, N, m |
| Momentum | momentum = mass × velocity | kg m/s, kg, m/s |
| Work done | work done = force × distance | J, N, m |
| Kinetic energy | kinetic energy = 0.5 × mass × speed² | J, kg, m/s |
| Gravitational potential energy | GPE = mass × gravitational field strength × height | J, kg, N/kg, m |
| Power | power = energy transferred ÷ time | W, J, s |
| Efficiency | efficiency = useful output energy ÷ total input energy | decimal or percentage |
| Pressure | pressure = force ÷ area | Pa, N, m² |
| Wave speed | wave speed = frequency × wavelength | m/s, Hz, m |
| Current, charge and time | charge = current × time | C, A, s |
| Potential difference and energy | energy transferred = charge × potential difference | J, C, V |
| Resistance | resistance = potential difference ÷ current | Ω, V, A |
| Electrical power | power = potential difference × current | W, V, A |
| Electrical energy | energy transferred = power × time | J, W, s |
| Transformer relationship | Vₚ ÷ Vₛ = Nₚ ÷ Nₛ | volts and turns |
| Magnification | magnification = image size ÷ object size | same length units |
Some equations are also expressed as required relationships rather than presented as a single formula. For example, energy can be transferred mechanically, electrically, by heating or by radiation. In an exam, the wording may test the idea behind the equation as well as the calculation.
Checklist by scenario
When learning a new equation
- Write the relationship in words before writing symbols.
- Identify every symbol and its unit.
- Check whether the quantity is a scalar, vector or signed value where relevant.
- Sketch the situation if it involves forces, moments, waves or circuits.
- Complete one straightforward example, then one in which the equation must be rearranged.
When answering a calculation
- Underline the values given in the question and identify the quantity required.
- Convert units before substituting. For example, centimetres must become metres when the equation requires metres.
- Choose the equation that contains the known values and the unknown.
- Rearrange algebraically before inserting numbers if the unknown is not already isolated.
- Substitute with brackets where needed, show the working and include a unit.
- Round only at the end, using sensible significant figures.
- Check the scale of the answer and ask whether its unit matches the quantity.
When revising with a formula sheet
- Cover the equation and recall it from the quantity names, not just its letter pattern.
- Practise finding each variable, not only the variable normally shown on the left.
- Mix topics in a short set of questions so that selecting the equation becomes part of the practice.
- Mark your answer using the method as well as the final value. A correct number reached without clear working may not earn every available mark.
- Record recurring errors in a small equation log: incorrect unit, wrong equation, rearrangement, substitution or arithmetic.
Worked example: rearranging an equation
A heater transfers 72,000 J of energy in 120 s. Calculate its power.
Start with power = energy transferred ÷ time. Substitute: power = 72,000 ÷ 120 = 600 W. The answer is reasonable because joules per second is equivalent to watts.
If the question instead gave power and time and asked for energy, rearrange to energy transferred = power × time. For example, a 600 W heater operating for 120 s transfers 600 × 120 = 72,000 J.
What to double-check
Exam board and specification: Confirm whether you are studying AQA, Edexcel or OCR, and whether your course is separate Physics or Combined Science. Use the board’s specification and the formula sheet for your examination series as the final authority.
Units and prefixes: Convert kJ to J, g to kg, cm to m and minutes to seconds when required. Prefixes such as kilo, milli, micro and nano change the numerical value. Keep a separate SI units and prefixes revision guide beside your equation practice.
Squared quantities: Area and speed squared are frequent sources of errors. A length of 20 cm is 0.20 m, but an area of 20 cm² must be converted as an area, not treated as 0.20 m².
Percentages: Efficiency can be written as a decimal or percentage. If the calculation gives 0.75, express it as 75% when the question asks for a percentage.
Graphs: A gradient may represent a physical quantity, but its unit depends on the axes. Read the axis labels and use two well-separated points rather than relying on a single plotted point.
Common mistakes
- Using mass in grams in an equation that requires kilograms.
- Confusing weight, measured in newtons, with mass, measured in kilograms.
- Using distance instead of displacement, or speed instead of velocity, when the question requires a directional quantity.
- Forgetting that kinetic energy contains speed squared.
- Using the wrong distance for a moment: it must be the perpendicular distance from the pivot to the line of action of the force.
- Reading a circuit equation without checking whether current, potential difference and resistance refer to the same component or section of circuit.
- Leaving out units or giving a unit that belongs to a different quantity.
- Relying on a triangle diagram without understanding the underlying relationship. Write the words first if you are unsure.
- Memorising an equation but not practising rearrangement. Questions commonly ask for a variable other than the one most familiar to you.
For more targeted practice, combine this sheet with a GCSE Physics revision checklist by topic and exam board, then use topic questions and mark schemes to identify where marks are being lost.
When to revisit
Return to this GCSE Physics formula sheet at the start of each topic, before a topic test, after completing a set of physics past papers and during the final weeks of exam preparation. Revisit it sooner if your school changes the paper being studied, you move between Combined Science and separate Physics resources, or your exam board issues an updated formula sheet.
Use this five-minute final check before an exam calculation:
- Have I selected the correct relationship?
- Are all quantities in compatible units?
- Have I rearranged correctly?
- Have I shown substitution and working?
- Does my final answer include a sensible unit and reasonable rounding?
Print or copy the equation table, hide one column at a time and test yourself. Then complete mixed questions without looking at the list. The goal is not simply to remember a formula; it is to recognise the physical situation, use the relationship accurately and communicate the result clearly.
