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OCR GCSE Physics topic map GCSE Physics · OCR Gateway J249

Equation sheet

Every equation in the OCR Gateway GCSE Physics A (J249) specification, grouped by topic. Each row says whether the specification lists it to recall or gives it on the equation sheet, whether it is Higher tier only, and whether it is examined only in GCSE Physics and not in Gateway Combined Science A (J250). The letters are the ones OCR uses. Each equation links the Physiworld lesson that teaches it; lessons open with a free account. The revision notes explain each topic with worked examples.

Recall the specification says learn it Given on the equation sheet Higher Higher tier only Physics only not in Combined Science

The equation sheet now prints everything. In the 2025, 2026 and 2027 exams the boards print every equation, recall ones included, on the sheet in the exam, and Ofqual has since decided the sheets stay for the rest of the current specifications. The recall equations are still the ones to know by heart: they save time, and the sheet will not tell you which equation a question needs. Check the sheet your board publishes for your exam year.

Energy

Equation	What it says, symbols and units	Lesson
E = ½mv² Recall	Energy of a moving object; double the speed and the kinetic energy is four times as big. E kinetic energy, J m mass, kg v speed, m/s	Dynamics 3 · Kinetic Energy
E = mgh Recall	Energy gained by a mass lifted through a height, near the Earth's surface. E gravitational potential energy gained, J m mass, kg g gravitational field strength, N/kg h height lifted, m	Dynamics 3 · Energy Conservation
E = ½kx² Given	Energy stored in a stretched spring, while it obeys Hooke's law. E elastic potential energy, J k spring constant, N/m x extension, m	Dynamics 6 · Elastic Potential Energy
W = Fs Recall	Work done by a force is the force times the distance moved along its line of action; it equals the energy transferred. W work done, J F force, N s distance along the line of the force, m	Dynamics 3 · Work Done
P = Wt Recall	Power is the work done each second. P power, W W work done, J t time, s	Dynamics 3 · Power
efficiency = useful energy outputtotal energy input (× 100%) Recall	The share of the input that ends up useful; it works the same with useful power output over total power input. Never more than 1, or 100%. efficiency a ratio or a percentage	Dynamics 3 · Power

Forces and motion

Equation	What it says, symbols and units	Lesson
W = mg Recall	Weight is the gravitational force on a mass; on Earth g is about 9.8 N/kg. W weight, N m mass, kg g gravitational field strength, N/kg	Gravity 1 · Mass & Weight
s = vt Recall	Distance travelled is (average) speed times time. s distance, m v speed, m/s t time, s	Dynamics 5 · Distance–Time Graphs
a = (v − u)t Recall	Acceleration is the change in velocity each second; a deceleration is a negative acceleration. a acceleration, m/s² v final velocity, m/s u initial velocity, m/s t time taken, s	Dynamics 5 · Velocity–Time Graphs
v² − u² = 2as Given	Links the start and end speeds to the distance, for constant acceleration, without needing the time. v final velocity, m/s u initial velocity, m/s a acceleration, m/s² s distance, m	Dynamics 5 · Equations of Motion
F = ma Recall	A resultant force accelerates a mass, in the direction of the force. F resultant force, N m mass, kg a acceleration, m/s²	Dynamics 1 · Newton’s Second Law
F = kx Recall	Up to the limit of proportionality, the extension of a spring is proportional to the force on it. F force, N k spring constant, N/m x extension, m	Dynamics 6 · Hooke’s Law
M = Fd RecallPhysics only	The turning effect of a force grows with the force and with its perpendicular distance from the pivot. M moment, N m F force, N d perpendicular distance from the pivot, m	Dynamics 7 · Moments
p = mv RecallHigher	Momentum is mass times velocity, and it has a direction. p momentum, kg m/s m mass, kg v velocity, m/s	Dynamics 2 · Momentum

Density, pressure and heating

Equation	What it says, symbols and units	Lesson
ρ = mV Recall	Density is the mass of each cubic metre of a material; a solid less dense than a liquid floats in it. ρ density, kg/m³ m mass, kg V volume, m³	Fluids 1 · Density
ΔE = mcΔθ Given	Energy needed to change the temperature of a mass; c is the energy to warm 1 kg by 1 °C. ΔE change in thermal energy, J m mass, kg c specific heat capacity, J/kg °C Δθ temperature change, °C	Thermal 1 · Specific Heat Capacity
E = mL Given	Energy needed to melt or boil a mass, with no change in temperature. E energy, J m mass, kg L specific latent heat, J/kg	Thermal 4 · Latent Heat
p = FA RecallPhysics only	Pressure is force per unit area: the same force on a bigger area gives a smaller pressure. p pressure, Pa (N/m²) F force at right angles to the surface, N A area, m²	Fluids 3 · Pressure
p = hρg GivenHigherPhysics only	Pressure due to a column of liquid grows with its height and density. p pressure, Pa h height of the column, m ρ density of the liquid, kg/m³ g gravitational field strength, N/kg	Fluids 3 · Pressure & Depth
pV = constant GivenPhysics only	For a fixed mass of gas at constant temperature, halve the volume and the pressure doubles (p₁V₁ = p₂V₂). p pressure, Pa V volume, m³	Thermal 8 · Squeeze a Gas

Waves and light

Equation	What it says, symbols and units	Lesson
v = fλ Recall	Wave speed is frequency times wavelength, for every kind of wave. v wave speed, m/s f frequency, Hz λ wavelength, m	Waves 1 · Wave Speed

Electricity

Equation	What it says, symbols and units	Lesson
Q = It Recall	Charge that flows is current times time; 1 C is 1 A for 1 s. Q charge, C I current, A t time, s	Electricity 3 · Current
V = IR Recall	Potential difference is current times resistance. V potential difference, V I current, A R resistance, Ω	Electricity 3 · Resistance
P = VI Recall	Electrical power is current times potential difference. P power, W I current, A V potential difference, V	Electricity 5 · Power & Fuses
P = I²R Recall	Power lost heating a resistance; a smaller current wastes much less, which is why the National Grid uses high voltage. P power, W I current, A R resistance, Ω	Electricity 11 · Why Such High Voltage?
E = Pt Recall	Energy transferred is power times time. E energy transferred, J P power, W t time, s	Electricity 10 · Paying for Energy
E = QV Recall	Energy transferred is the charge times the potential difference it moves through. E energy transferred, J Q charge, C V potential difference, V	Electricity 3 · Potential Difference

Magnetism and electromagnetism

Equation	What it says, symbols and units	Lesson
F = BIl GivenHigher	Force on a current-carrying wire at right angles to a magnetic field. F force, N B magnetic flux density, T I current, A l length of wire in the field, m	Electricity 4 · The Motor Effect
V_pV_s = N_pN_s GivenHigherPhysics only	A transformer changes an alternating voltage in the ratio of its turns. V_p, V_s p.d. across primary and secondary coil, V N_p, N_s number of turns on each coil	Electricity 11 · Building the Grid
V_pI_p = V_sI_s Given	For a 100% efficient transformer, power in equals power out: step the voltage up and the current goes down. I_p, I_s current in primary and secondary coil, A V_p, V_s p.d. across each coil, V	Electricity 11 · Why Such High Voltage?

Written in Physiworld's own words from the OCR specification. Combined Science students can skip the Physics only rows.

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