A 1:10 scale model of a tractor-trailer rig is tested in a wind tunnel. The model frontal area is \(A_{m}=0.1 \mathrm{~m}^{2}\). When tested at \(V_{m}=75 \mathrm{~m} / \mathrm{s}\) in standard air, the measured drag force is \(F_{D}=350 \mathrm{~N}\). Evaluate the drag coefficient for the model conditions given. Assuming that the drag coefficient is the same for model and prototype, calculate the drag force on a prototype rig at a highway speed of \(90 \mathrm{~km} / \mathrm{hr}\). Determine the air speed at which a model should be tested to ensure dynamically similar results if the prototype speed is \(90 \mathrm{~km} / \mathrm{hr}\). Is this air speed practical? Why or why not?