Mathematics: notes and practice questions
- This topic covers the fundamental mathematical skills for solving physics problems and interpreting data.
- Perform basic arithmetic, algebraic manipulations, and trigonometric calculations.
- Use scientific notation, calculate mean, range, and rates of change.
- Understand direct and inverse proportionality.
- Identify scalar and vector quantities, and perform vector addition, subtraction, and resolution.
- Calculate and interpret percentage change and percentage uncertainty.
- Use radian measurement and convert between degrees and radians.
How it is examined
Paper 1B is built on this subtopic, and it leaks into Paper 2 constantly. Real May 2025 evidence:
- Uncertainty propagation. Paper 1B TZ1 question 1(b)(i), 2 marks: calculate a density and its absolute uncertainty from (10.6 ± 0.2) cm³ and (10.82 ± 0.01) g. The mark scheme allowed the mass uncertainty to be neglected provided the candidate said so, and instructed "DO NOT penalize for SF". - Precision and unit conversion. Question 1(b)(ii), 1 mark, was purely "State your answers in kg m⁻³ and with correct precision", answer 1020 ± 20. Here precision is the mark, and the notes required 3 significant figures with matching precision in the uncertainty. - Gradient from a best-fit line. Question 2(c)(i), 2 marks, required the candidate to use two points spanning more than half the line, with the note "Look for Δx ≥ 0.3". - Maximum-gradient line. Question 2(c)(ii), 1 mark, "draw max from lower end of lower error bar to upper end of upper error bar". - Uncertainty in a gradient. Question 2(c)(iii), 2 marks, accepted a range: "Look for working leading to 0.1 ≤ Δn ≤ 0.2". - Fundamental units. Paper 2 TZ1 question 1(b), both levels, ended with "State the fundamental SI unit for your answer", answer kg m⁻¹. Note the two rules pulling in opposite directions. Instruction 13 in every mark scheme says do not penalize errors in units or significant figures unless the Notes say otherwise. But the Notes say otherwise often, and in Paper 1B they say it about precision specifically. The default is lenient; the exceptions are where the skill is the point of the question.
The data booklet carries the SI prefixes, the fundamental and derived units, the unit conversions and the constants. It does not carry the uncertainty propagation rules, so the student must know that fractional uncertainties add for a product or quotient, that absolute uncertainties add for a sum or difference, and that a power multiplies the fractional uncertainty.
- Use basic arithmetic and algebraic calculations to solve problems.
- Calculate areas and volumes for simple shapes.
- Carry out calculations involving decimals, fractions, percentages, ratios, reciprocals, exponents and trigonometric ratios.
- Carry out calculations involving logarithmic and exponential functions.
The formal process of dimensional analysis will not be assessed, although checking an expression using units is expected.
Practice questions
6 questions · 1 easy · 3 medium · 2 hardQuestion 1
EasyPaper 1A · calculator1 markA student measures the mass of a metal block as g and its volume as cm. What is the fractional uncertainty in the calculated density of the block?
A. 0.02
B. 0.04
C. 0.06
D. 0.08
Recall how fractional uncertainties combine when quantities are multiplied or divided. The fractional uncertainty of a quantity is given by .
Question 2
MediumPaper 2 · calculator2 marks(a) A large wind turbine generates electrical power at a rate of when its blades are rotating at . Calculate the magnitude of the torque exerted by the wind on the turbine shaft.
Remember to convert the angular speed from revolutions per minute to radians per second before using the power-torque relationship.
Question 3
HardPaper 1A · calculator1 markThe characteristic impedance of free space, , is a physical constant relating the magnitudes of the electric and magnetic fields of electromagnetic radiation travelling through free space. It is given by the expression . What are the fundamental SI units of ?
A.
B.
C.
D.
Recall that impedance has the same units as resistance. Use the definition of resistance in terms of potential difference and current () and express these in fundamental SI units. Alternatively, derive the fundamental units of and from laws such as Ampere's law and Coulomb's law, then combine them as required by the expression for .
Question 4
MediumPaper 2 · calculator7 marksA student performs an experiment to determine the resistivity of a metal wire. The resistance , length , and diameter of the wire are measured.
(a) The diameter is measured with a micrometer screw gauge. State one experimental precaution that should be taken to ensure this measurement is accurate.
(b) The following data are collected:
Resistance
Length
Diameter
Calculate the resistivity of the wire and its absolute uncertainty.
(c) State the value of the resistivity with its uncertainty to an appropriate number of significant figures.
(d) The accepted value for the resistivity of nichrome at the experimental temperature is . Deduce, using your answer from (c), whether the wire is likely to be made of nichrome.
Think about what could cause inconsistent readings when using a micrometer. Is there any initial error to check for before taking measurements?
First, write down the formula for resistivity in terms of resistance, length, and diameter. Remember to convert all quantities to SI units before substituting. For the uncertainty, recall the rule for combining fractional uncertainties for multiplication, division, and powers.
The number of decimal places in your value should match the number of decimal places in your uncertainty. The uncertainty itself is usually quoted to one significant figure.
Calculate the upper and lower bounds of your experimental value using the uncertainty. Check if the accepted value falls within this range.
Question 5
HardPaper 1A · calculator1 markIn a photoelectric effect experiment, a graph of stopping potential is plotted against the wavelength of the incident light for a particular metal surface. What is the magnitude of the gradient of the graph at wavelength ?
A.
B.
C.
D.
Start with the photoelectric effect equation relating maximum kinetic energy, frequency, and work function. Express this equation in terms of stopping potential and wavelength . The gradient of a graph of versus is given by the derivative .
Question 6
MediumPaper 2 · calculator13 marksA small spherical steel ball is released from rest at the surface of a tall column of glycerin.
The following data are available:
radius of the steel ball =
density of steel =
density of glycerin =
viscosity of glycerin =
acceleration due to gravity
(a) (i) Calculate the volume of the steel ball.
(a) (ii) Calculate the initial acceleration of the steel ball.
(b) Describe how the acceleration of the steel ball changes as it falls through the glycerin.
(c) (i) Explain why the steel ball eventually reaches a constant velocity.
(c) (ii) Determine the terminal velocity of the steel ball.
Recall the formula for the volume of a sphere. Ensure consistent units before calculation.
Consider all forces acting on the ball at the moment it is released. Apply Newton's second law. Remember that drag force is zero initially.
Consider the forces acting on the ball as its speed increases.
Think about the condition for zero acceleration.
At terminal velocity, the net force is zero. The drag force can be calculated using Stokes' Law: .
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Where marks are lost
- Stopping one step short of the conclusion. Two numbers and no sentence is two marks out of three.
- Answering a procedure question with a platitude.
- Losing precision in Paper 1B. Uniquely to this paper, quoting the right number badly loses marks.