5054_s26_qp_12 — 2026 May-June Physics 5054 Question Paper 1 Variant 2 · Cambridge CAIE O Level

Confusing momentum with moment of a force, and errors in conservation of momentum calculations

“A significant number of candidates could not define momentum or confused momentum with the moment of a force.”— 5054 Paper 2, May/June 2023

How to fix: Momentum = mass x velocity (a property of a moving object). Moment = force x perpendicular distance from the pivot (a turning effect). In conservation of momentum problems, after a collision where objects stick together, the combined mass is the sum of BOTH masses. Write: m1v1 + m2v2 = (m1 + m2) x v_final.

Distance-time and speed-time graph misinterpretation — confusing acceleration on one graph type with the other

“The shape of the distance-time graph when a car is accelerating was not always clear to candidates.”— 5054 Paper 1, May/June 2023

How to fix: Speed-time graph: gradient = acceleration, area under graph = distance. Distance-time graph: gradient = speed, and a curve means the object is accelerating. To find instantaneous speed from a distance-time graph, draw a tangent and find its gradient — do NOT divide total distance by total time (that gives average speed).

Newton's third law misunderstood — pairing wrong force types together

“The third law of motion is often misunderstood. The confusion arises as a normal contact force is sometimes referred to as a normal reaction. Candidates should be made aware that the pair of forces described as action and reaction in Newton's third law should always be of the same type.”— 5054 Paper 1, May/June 2023

How to fix: Newton's third law force pairs must be: (1) the same type of force (both gravitational, both contact, both electromagnetic), (2) acting on two DIFFERENT objects, (3) equal in magnitude and opposite in direction. Weight (gravitational pull of Earth on object) is paired with the gravitational pull of the object on Earth — NOT with the normal contact force from the surface.