Physics

Viscous drag for the first, b = beta * D. Why D and not D^2 here. Then quadratic: model as "knocking molecules out of the way", make sense of v^2 (one power to speed up the molecules, and one more power because we "sweep out" more volume per second as we move), and thus sensemake c = (1/2) c_d rho(air) Area. ................
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