GCSE Physics Equations List: Required Formulae, Units and When to Use Them

Overview

GCSE Physics often feels difficult for one reason more than any other: students know the topic in words, but struggle to turn that knowledge into a calculation. That is usually not a maths problem. It is an equation-selection problem.

This hub aims to fix that. Rather than giving a bare physics equations list GCSE students have to decode for themselves, it organises the most important GCSE physics formulae by topic and shows:

• what each equation is used for
• the standard symbol meanings
• the expected units
• common rearrangements
• mistakes that cost marks

Exam boards vary slightly in wording and layout, and some students take GCSE Physics while others take Combined Science. Because of that, the safest approach is to use this page as a revision hub and then cross-check the exact specification and formula sheet wording for your own course.

A good rule for all GCSE physics equations is this: do not start by hunting for letters that match. Start by asking what physical quantity the question wants, what quantities have been given, and what topic the question belongs to. That small pause often stops the most common error in physics exam technique: choosing a familiar equation too early.

Another useful habit is the unit check. If your answer is supposed to be in joules but your working combines values that would lead to newtons, seconds or metres in the wrong way, something has gone wrong. Unit awareness is not extra revision. It is part of understanding the equation.

Topic map

Below is a topic-by-topic map of core GCSE physics equations, with notes on when to use them and how to sense-check your answer.

1. Motion

Speed equation: speed = distance ÷ time

Symbols often used: v = s / t

Units: speed in m/s, distance in m, time in s

Use this when the question asks how fast something moves on average across a measured distance.

Common rearrangements:

• distance = speed × time
• time = distance ÷ speed

Exam-use note: many GCSE questions mix units, especially kilometres and hours versus metres and seconds. Convert before substituting. If the question later asks for stopping distance, braking distance or thinking distance, this simple speed equation may only be one step of the problem rather than the final answer.

Acceleration equation: acceleration = change in velocity ÷ time

Symbols often used: a = (v - u) / t

Units: acceleration in m/s², velocity in m/s, time in s

Use this when an object speeds up, slows down or changes direction.

Common rearrangement:

• v = u + at

Exam-use note: if the object is slowing down, the acceleration may be negative. Students often lose marks by using speed values carelessly instead of thinking about velocity change.

2. Forces and motion

Weight equation: weight = mass × gravitational field strength

Symbols often used: W = mg

Units: weight in N, mass in kg, gravitational field strength in N/kg

Use this when a question gives mass and asks for the force due to gravity.

Common mistake: confusing mass and weight. Mass is measured in kilograms. Weight is a force measured in newtons.

Force equation: force = mass × acceleration

Symbols often used: F = ma

Units: force in N, mass in kg, acceleration in m/s²

Use this when a resultant force causes acceleration.

Exam-use note: check whether the force in the question is the resultant force or just one force acting. Free-body thinking matters even at GCSE level.

Momentum: momentum = mass × velocity

Symbols often used: p = mv

Units: kg m/s

Use this in collision and impact questions.

Force and change in momentum: force = change in momentum ÷ time

Use this when impact time is part of the question, for example in safety features such as airbags, crumple zones or helmets.

Exam-use note: this is a frequent explanation question as well as a calculation one. A longer impact time means a smaller force for the same change in momentum.

3. Energy

Work done: work done = force × distance moved in the direction of the force

Symbols often used: W = Fs

Units: joules, because N × m = J

Use this when a force causes movement.

Kinetic energy: kinetic energy = 0.5 × mass × speed²

Symbols: Ek = 1/2 mv²

Units: J

Use this when an object is moving.

Common mistake: forgetting to square the speed. This is one of the most important checks in GCSE physics equations work.

Gravitational potential energy: GPE = mass × gravitational field strength × height

Symbols: Ep = mgh

Units: J

Use this when an object is raised above the ground.

Elastic potential energy: elastic potential energy = 0.5 × spring constant × extension²

Symbols: Ee = 1/2 ke²

Use this for springs and elastic systems where the extension is measured from the natural length.

Exam-use note: extension is not the full stretched length. It is how much longer the spring has become.

4. Power and efficiency

Power: power = energy transferred ÷ time

Also: power = work done ÷ time

Symbols: P = E / t

Units: watts, where 1 W = 1 J/s

Use this when the question is about how quickly energy is transferred.

Efficiency: efficiency = useful energy output ÷ total energy input

Or useful power output ÷ total power input

Efficiency can be written as a decimal or percentage.

Exam-use note: if the answer is greater than 1 or greater than 100%, there is almost certainly a mistake.

5. Electricity

Charge flow: charge = current × time

Symbols: Q = It

Units: coulombs, amperes, seconds

Use this when current flows for a measured time.

Potential difference, current and resistance: potential difference = current × resistance

Symbols: V = IR

Units: volts, amperes, ohms

This is one of the central equations in GCSE electricity and appears in many forms. Rearranging confidently is essential:

• I = V / R
• R = V / I

Electrical power: power = current × potential difference

Symbols: P = IV

Units: W

Electrical energy transferred: energy = power × time

Symbols: E = Pt

Often combined with power equations in appliance questions.

Exam-use note: be very careful with time units here. Bills and appliance use often involve hours, but some formula work expects seconds.

6. Density and pressure

Density: density = mass ÷ volume

Symbols: ρ = m / V

Units often kg/m³, though questions may provide g/cm³

Use this in material questions, floating and sinking contexts, or required practical analysis.

Pressure: pressure = force ÷ area

Symbols: p = F / A

Units: pascals, where 1 Pa = 1 N/m²

Use this when a force is spread over an area, for example sharp blades, snowshoes or tyres.

7. Waves

Wave speed: wave speed = frequency × wavelength

Symbols: v = fλ

Units: m/s, Hz, m

Use this for all wave types where frequency and wavelength are involved.

Exam-use note: frequency is measured in hertz, not seconds. Period and frequency are related but not interchangeable.

8. Radioactivity

Activity: activity = count rate or decay rate in becquerels

Not every radioactivity question is a formula question, but students should still be comfortable with half-life calculations, often using proportional reasoning rather than a fixed equation.

Exam-use note: radioactivity marks are frequently won through careful interpretation of graphs, tables and decay descriptions rather than heavy algebra.

9. Heating and particle model

Specific heat capacity: change in thermal energy = mass × specific heat capacity × temperature change

Symbols: ΔE = mcΔθ

Units: J, kg, J/kg°C or J/kg°C equivalent, °C

Use this when heating changes temperature but not state.

Common mistake: using this during melting or boiling, where the temperature stays constant.

10. Light and lenses

Magnification: magnification = image height ÷ object height

Use this in optics questions involving diagrams, ray tracing or measured images.

Exam-use note: this often appears in practical-style questions where accurate measurement from a diagram matters.

Related subtopics

Knowing the GCSE physics formula sheet is only one part of doing well. The subtopics below make the equations easier to use under exam pressure.

Units and conversions

Many lost marks come from unit mismatch, not hard physics. Build a short conversion list you know by heart: minutes to seconds, hours to seconds, centimetres to metres, grams to kilograms, and centimetres cubed to metres cubed where needed. If your GCSE physics units are weak, the equations will feel harder than they are.

Rearranging equations

Students often say they know the formula but cannot use it because the question asks for a different variable. This is where rearranging matters. Practise each core equation in all directions, especially:

• V = IR
• ρ = m / V
• p = F / A
• v = s / t
• P = E / t

Do not rely entirely on formula triangles. They can help at first, but long-term understanding is better if you can manipulate the equation directly.

Significant figures and rounding

Most GCSE mark schemes allow sensible rounding, but careless early rounding can create avoidable differences. A safe habit is to keep more digits in your calculator during the working and round only at the end.

Required practicals

Equations become much easier when tied to measurement. In density, resistance, specific heat capacity or wave questions, ask yourself what would actually be measured in a practical. That makes the symbols less abstract and improves memory.

Past papers and mark schemes

Equations should be revised in context, not as a disconnected list. Use physics past papers and topic questions to see how examiners phrase the same formula in different ways. Mark schemes are especially useful for spotting whether a question wants a numerical answer only, a substitution line, a unit, or an explanatory sentence alongside the calculation.

If you want to improve how you revise calculations away from a screen, it is worth reading Why Paper Can Beat Screens in Physics Revision. For students using digital tools, How to Tell If an AI Physics Tutor Is Teaching You the Wrong Thing is a useful reminder that fast help is not always accurate help.

How to use this hub

The most effective way to use a GCSE physics equations list is little and often. Do not wait until a mock exam to look at the formulae. Build them into your weekly revision.

A practical method looks like this:

1. Start by topic. Revise energy, electricity, waves or forces one at a time. Attach each equation to the topic story, not just the symbols.
2. Learn the units with the equation. Treat the units as part of the formula, not an afterthought.
3. Practise one rearrangement per equation. If you can only use the formula in the printed order, you are not exam-ready yet.
4. Do three question types. One straightforward substitution, one unit-conversion question and one worded exam-style problem.
5. Check with mark schemes. Notice how often marks are awarded for method, substitution, unit and final answer separately.

You can also turn this page into a personal revision tool. For each equation, add a note such as:

• "I confuse mass and weight here"
• "Need to square the speed"
• "Remember extension is stretched length minus original length"
• "Convert minutes to seconds first"

That kind of annotation is far more useful than copying a polished physics formula sheet without thinking.

For teachers, tutors and independent learners, this hub also works as a diagnosis tool. If a student is consistently getting calculation questions wrong, check whether the real issue is:

• equation choice
• unit conversion
• rearrangement
• calculator use
• misreading the wording

The fix depends on the cause. Extra question practice alone will not solve the problem if the underlying weakness is, for example, units or algebra.

When to revisit

This hub is most useful when revisited at the right moments, not just before the final exam. Come back to it when:

• you begin a new GCSE physics topic and want to see which equations belong to it
• you start doing physics past papers and notice repeated calculation errors
• you receive a test back and need to identify whether marks were lost on method, units or equation choice
• your course provides a formula sheet and you want to turn it into genuine understanding
• you move from learning content to practising timed exam technique

A simple action plan for the next revision session is:

1. Pick one topic from this page.
2. Write the equations from memory.
3. Add the units beside every symbol.
4. Rearrange each one at least once.
5. Complete two or three exam questions on that topic.
6. Mark them and note your most common error.

If you repeat that process steadily, the equations stop feeling like isolated facts and start becoming tools you can use calmly under pressure. That is the real aim of GCSE physics revision: not memorising symbols for their own sake, but knowing when an equation applies, how to use it cleanly, and how to show the examiner exactly what you understand.

As this topic expands, this hub can be revisited alongside topic questions, worked solutions and specification-specific notes. The strongest revision pages are the ones that stay useful after the first read. A GCSE physics equations guide should do exactly that.