9702_m26_er — 2026 March Physics 9702 Examiner Report · Cambridge CAIE AS & A Level

Unit conversion errors — powers of ten wrong when converting cm, mm, km

“There was a significant number of candidates that made errors converting the mass in grams into kilograms and the length from centimetres into metres.”— Paper 2, March 2025

How to fix: Write every conversion explicitly: 1 cm = 10⁻² m, 1 mm = 10⁻³ m, 1 km = 10³ m. For AREA: cm² to m² = ×10⁻⁴ (not ×10⁻²). For VOLUME: cm³ to m³ = ×10⁻⁶. Always write the conversion as a separate line in your working.

Missing key words in definitions — 'resultant', 'per unit', 'moving'

“A significant number gave 'mass times acceleration' which is a valid way to calculate force, but is not the definition of force required by the syllabus.”— Paper 2, March 2025

How to fix: Learn definitions EXACTLY: Force = rate of change of momentum (NOT mass × acceleration). Gravitational field = force PER UNIT MASS. Electric field = force per unit POSITIVE charge. Equilibrium = RESULTANT force is zero AND RESULTANT torque is zero. Half-life = time for ACTIVITY to halve (not 'number of nuclei').

Swapping sine and cosine when resolving vectors

“Candidates had particular difficulty resolving vectors into perpendicular components. Candidates should be able to select the correct trigonometric function for each problem.”— Paper 1, March 2025

How to fix: Draw a right-angle triangle. The component ADJACENT to the angle uses cosine. The component OPPOSITE to the angle uses sine. If the angle is measured from the horizontal: horizontal = F cos θ, vertical = F sin θ. Always sketch the triangle — don't guess.