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F = ma (11–17)
Dynamics
FMA-2026-12 · 2026 F = ma (AAPT)

2026 F = ma Exam — Question 12

A wake surfer of total mass M (surfer plus board) is being towed at a constant horizontal velocity v across a flat lake. The wakeboard has a specific geometry such that, at this speed, it is partially submerged and provides a static buoyant force FB (where FB < M g). To support the remainder of the weight, the board moves with an angle of attack θ relative to the horizontal water surface. Assume that the water exerts a reaction force strictly normal to the bottom surface of the board. Which of the following expressions represents the horizontal tension T in the tow rope required to maintain this constant velocity?
Source: Question 12, 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.