2011 F = ma Exam — Question 24 — Physics Guide

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FMA-2011-24 · 2011 F = ma (AAPT)

2011 F = ma Exam — Question 24

24. A turntable is supported on a Teﬂon ring of inner radius R and outer radius R+δ (δ ≪R), as shown in the diagram. To rotate the turntable at a constant rate, power must be supplied to overcome friction. The manufacturer of the turntable wishes to reduce the power required without changing the rotation rate, the weight of the turntable, or the coeﬃcient of friction of the Teﬂon surface. Engineers propose two solutions: increasing the width of the bearing (increasing δ), or increasing the radius (increasing R). What are the eﬀects of these proposed changes? R — Source: Question 24, 2011 F = ma Exam, © 2011 American Association of Physics Teachers (AAPT) and the U.S. Physics Team. Adapted by PhysicsTrainer: reformatted into a separate question and answer choices for online multiple-choice practice; any shared setup from nearby questions is repeated here. Not affiliated with or endorsed by AAPT or the U.S. Physics Team.

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F = ma problems are © the American Association of Physics Teachers (AAPT) and the U.S. Physics Team, the original source, and are used with permission. Problems shown here are adaptations: they have been reformatted by Physics Guide into separate question and answer-choice pieces for online multiple-choice practice. Physics Guide is an independent student project and is not affiliated with, endorsed by, operated by, or supported by AAPT, F = ma, USAPhO, or the U.S. Physics Team.

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