A thin horizontal beam XY is freely hinged at point Y to a vertical wall. The beam is held stationary by a cable XZ which is attached to the wall at point Z. [Figure 12.1] The beam supports a weight W at point X. The forces in the cable and the beam are F_C and F_B respectively. Which vector triangle represents the forces acting on point X? [Figure 12.2]
✓ Correct Answer
The correct answer is A: Diagram showing three vectors forming a closed triangle: W vertically down, F_C upwards and left, F_B horizontally right, arranged head-to-tail.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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