AQA GCSE science calculations
Every calculation on the AQA GCSE specifications · part of the free Calculation Climb
All 40 calculations you can be asked to do in AQA GCSE Biology, Chemistry and Physics — each with the formula, the steps in order, and a worked example.
AQA GCSE Biology calculations11
Converting units (mm, µm, nm)Cells and microscopes work in tiny units, and you have to switch between them: 1 mm = 1000 µm and 1 µm = 1000 nm.Estimating population sizeTwo exam methods. Quadrats: mean per quadrat × how many quadrat-areas fit in the whole area.Genetic ratios & probabilityFrom a Punnett square you predict ratios and chances.Light intensity and the inverse square lawHigher tierLight does not get weaker steadily as you move away from a lamp — it drops off much faster than that.Magnification (image ÷ actual)How many times bigger the image is than the real object: magnification = image size ÷ actual size.Mean, median, mode & rangeWays to summarise a set of results.PercentageA percentage is a number out of 100.Percentage changeHow much something has gone up or down, as a percentage of where it started: (change ÷ starting value) × 100.Rate (change ÷ time)A rate is how much something changes ÷ how long it took.Reading & interpolating graphsOften you have to read a value between marked points.Surface area : volume ratioFor a cube: surface area = 6 × side², volume = side³.
AQA GCSE Chemistry calculations12
Ar from isotopic abundancesNot the same as simply reading Ar off the periodic table.Atom economyThe percentage of the reactant mass that ends up as the useful product.Concentration (g/dm³)How much solute is dissolved per dm³ of solution: concentration = mass (g) ÷ volume (dm³).Concentration (mol/dm³)Higher tierConcentration measured in moles of solute per dm³ of solution: concentration = moles ÷ volume (dm³).Conservation of massIn a reaction no atoms are created or destroyed, so the total mass of reactants = total mass of products.Gas volumes (24 dm³)Higher tierAt room temperature and pressure, one mole of any gas takes up 24 dm³.Moles and massHigher tierAlmost every chemistry calculation at Higher tier runs through moles.Percentage by massThe percentage of a compound's mass that comes from one element — and, on AQA papers, its twin: the percentage of a mixture (an alloy, an ore, a…Percentage yieldHow much product you actually got, compared with the maximum you could in theory have made: % yield = (mass actually made ÷ maximum theoretical…Reacting massesHigher tierUse the balanced equation's ratio to find how much product forms (or reactant is needed).Relative formula mass (Mr)The relative formula mass (Mr) is the mass of a whole formula — you get it by adding up the Ar of every atom in it.Titration calculationThe boss level — find an unknown concentration from a titration by chaining three things you already know: moles = concentration × volume, the…
AQA GCSE Physics calculations17
Acceleration (a = Δv ÷ t)Acceleration is how quickly velocity changes: a = change in velocity ÷ time.Charge (Q = I t)Charge = current × time: Q = I t.Density (ρ = m ÷ V)Density = mass ÷ volume — how much mass is packed into a volume.Gravitational PE (E = m g h)The energy stored when you lift something: E = m g h (mass × gravitational field strength × height).Hooke’s law (F = k e)For a spring, force = spring constant × extension: F = k e.Kinetic energy (E = ½ m v²)The energy of a moving object: E = ½ m v².Momentum (p = m v)Higher tierMomentum = mass × velocity: p = m v.Ohm’s law (V = I R)Potential difference = current × resistance: V = I R.Power (P = E ÷ t)Power = energy transferred ÷ time (or work done ÷ time).Pressure in a liquid (p = h ρ g)Higher tier · Triple onlyThe pressure at a depth in a liquid: p = h ρ g (depth × density × gravitational field strength).Pressure (p = F ÷ A)Pressure = force ÷ area, in pascals (Pa = N/m²).Specific heat capacity (E = m c Δθ)The energy to change something’s temperature: E = m c Δθ (mass × specific heat capacity × temperature change).Specific latent heat (E = m L)Energy to melt or boil a substance with no temperature change: E = m L, where L is the specific latent heat (J/kg).Speed (v = s ÷ t)Speed = distance ÷ time. Distance in metres, time in seconds gives speed in m/s.Wave speed (v = f λ)Wave speed = frequency × wavelength: v = f λ.Weight (W = m g)Weight is the force of gravity on a mass: W = m g.Work done (W = F s)Work done = force × distance moved (in the direction of the force).
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