2011 F = ma Exam — Question 7 — Physics Guide

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FMA-2011-07 · 2011 F = ma (AAPT)

2011 F = ma Exam — Question 7

7. An ice skater can rotate about a vertical axis with an angular velocity ω0 by holding her arms straight out. She can then pull in her arms close to her body so that her angular velocity changes to 2ω0, without the application of any external torque. What is the ratio of her ﬁnal rotational kinetic energy to her initial rotational kinetic energy? √ — Source: Question 7, 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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