The 170-lb skier is schussing on a 25 ∘ slope. At the instant shown, he is moving at 40 ft/s .The kinetic coefficient of friction between his skis and the snow is μk = 0.08. Aerodynamic drag exerts a resisting force on him of magnitude 0.015v2 , where v is the magnitude of his velocity. If he makes no attempt to check his speed, how long does it take for it to increase to 60 ft/s
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