1. The problem statement, all variables and given/known data Determine the power of a windmill using constants where appropriate. 2. Relevant equations P = Fv K = (1/2)mv2 3. The attempt at a solution Dynamics Method P = Fv In time Δt, Δm amount of wind passes through the windmill, at speed of v. Δp = vΔm = v(AρΔx) Dividing both sides by Δt, F = Aρv2 P = Fv = Apv3 Energy Method In time Δt, Δm amount of wind passes through the windmill, with KE of (1/2)(Δm)v2 . Energy Transferred = (1/2)(Δm)v2 = (1/2)(ρAΔx)v2 Dividing both sides by Δt, Power = (1/2)ρAv3 I've thought a long time about this; both methods make sense, but why are they different? Appreciate any help guys!