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F = ma (First 10)
Dimensional Analysis
FMA-2026-02 · 2026 F = ma (AAPT)

2026 F = ma Exam — Question 2

A series of dominoes are stood upright in a line. The dominoes have mass density ρ, height h, and spacing d between them. When the first domino is knocked over, a wave of falling dominoes propagates down the line with speed v. Now, a second set of dominoes is set up identically, but with all dimensions (h and d) scaled by λ. The mass density is the same. Let v ′ denote the wave speed of the scaled system. Which of the following best describes how v ′ depends on λ?
Source: Question 2, 2026 F = ma Exam, © 2026 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.