2013 F = ma Exam — Question 16 — Physics Guide

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F = ma (11–17)

Gravitation

FMA-2013-16 · 2013 F = ma (AAPT)

2013 F = ma Exam — Question 16

16. Inspired by a problem from the 2012 International Physics Olympiad, Estonia. A very large number of small particles forms a spherical cloud. Initially they are at rest, have uniform mass density per unit volume ρ0, and occupy a region of radius r0. The cloud collapses due to gravitation; the particles do not interact with each other in any other way. How much time passes until the cloud collapses fully? (The constant 0.5427 is actually q 3π 32 .) — Source: Question 16, 2013 F = ma Exam, © 2013 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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