H1 Physics 8867 · Nov 2023PhysicsPaper 2Widespread errors

Paper 2 Q3 — Tension in an angled wire

Forces in equilibrium — resolving tension; the effect of wire length on angle and tension

What the examiners said

“Some answers confused gravitational field strength and gravitational force… One common error was to state there was no external force on the object. Few candidates considered the vertical component of the tension… Some candidates struggled as they considered the angle to remain fixed for all lengths of wire.”

Item 1 — defining gravitational field strength

Which statement defines gravitational field strength at a point?

Examiner report: “Answers confused gravitational field strength and gravitational force.”

Item 2 — equilibrium of the hanging picture

A picture of weight 8.0 N hangs from a nail by a wire whose two halves each make 25° with the horizontal. What is the tension in the wire?

Examiner report: “Few candidates considered the vertical component of the tension and the weight explicitly.”

Item 3 — a longer wire

The same picture is re-hung with a longer wire on the same nail and fixing points. What happens to the angle θ (to the horizontal) and to the tension?

Examiner report: “Some candidates considered the angle to remain fixed at 25° for all lengths of wire.”

Explore — wire length, angle and tension

Lengthen the wire and watch the geometry set the angle, and the angle set the tension. The red line marks a breaking tension of 42 N — can this wire ever hold a 40 N picture?

Weight of picture (N): 8 Angle θ (set by wire length) (°): 25

Set W = 40 N and sweep the angle: even at θ = 85° the tension only falls towards W/2 = 20 N — so yes, a long enough wire holds it. The exam’s deeper point: check whether the improvement is sufficient, not just in the right direction.

Original reconstruction inspired by the misconceptions described in the Singapore-Cambridge GCE A-Level H1 Physics 8867 November 2023 Examiner Report. Not the actual examination question. For classroom exploration.

Made by lookang, using Claude Fable 5. More resources: iwant2study.org