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F = ma (11–17)
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FMA-2007-20 · 2007 F = ma (AAPT)

2007 F = ma Exam — Question 20

20. A point-like mass moves horizontally between two walls on a frictionless surface with initial kinetic energy E. With every collision with the walls, the mass loses ½ its kinetic energy to thermal energy. How many collisions with the walls are necessary before the speed of the mass is reduced by a factor of 8?
Source: Question 20, 2007 F = ma Exam, © 2007 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.