The drag force, Fd, imposed by the surrounding air on a

Chapter 2, Problem 2.21

(choose chapter or problem)

The drag force, \(F_{\mathrm{d}}\), imposed by the surrounding air on a vehicle moving with velocity V is given by

\(F_{\mathrm{d}}=C_{\mathrm{d}} \mathrm{A} \frac{1}{2} \rho \mathrm{V}^{2}\)

where \(C_{\mathrm{d}}\) 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 \(C_{\mathrm{d}}=0.28, \mathrm{A}=25 \mathrm{ft}^{2}\), and  \(\rho=0.075 \mathrm{lb} / \mathrm{ft}^{2}\)..