A-LevelPhysicsMotion in a circleFeb/Mar 2019Paper 1 Q121 Mark
A fairground ride consists of four carriages connected to a central vertical pole, as shown in the following view from above. [Figure 12.1] A motor rotates the central pole about its axis. This results in the four carriages each moving along a circular path. The distance from the middle of each carriage to the centre of the pole is 3.20 m. When they are moving, each carriage experiences an air resistance force of 85.0 N. Assume that there are no other significant resistive forces. Which torque does the motor need to apply to the pole to keep the system rotating at constant maximum speed?
A5.44 Nm
B272 Nm
C544 Nm
D1090 Nm
✓ Correct Answer
The correct answer is D: 1090 Nm
📋 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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