The drag force, Fd, imposed by the surrounding air on a vehicle moving with velocity V is given by Fd CdA1 2 rV2 where Cd is a constant called the drag coefficient, A is the projected frontal area of the vehicle, and is the air density. Determine the power, in hp, required to overcome aerodynamic drag for an automobile moving at (a) 25 miles per hour, (b) 70 miles per hour. Assume Cd 5 0.28, A 5 25 ft2 , and 5 0.075 lb/ft2 .

Notes Taken for EMT on March 28, 2016 First Order System with a Harmonic input Recall, for a step input, we had F(t) = 0 @ t = 0 A F(t) = a 0 @ t > 0 For a Harmonic Input to the 1 order system, we have F(t) = 0 @ t =0 A F(t) = sin(ωt ) for t > 0 a 0 amplitude frequency The solution for harmonic input is A −t x(f) = a0 −1 τ 2 sin[ωt−tan ωt )]+Ce √ 1+(ωt) a 1 again, τ = a0 The Phase Shift is defined as −1 Φ(ω) = tan (ωt) (ϕ is in radians) ϕ(ω) The steady state response lags by time delay ωt = & ω is the frequency of the si