C= f/1/2pv²A
where, C = drag coefficient (unitless) V = air speed inside the wind tunnel (ft/s) F = measured drag force(lbs) A = frontal area of the car (ft?) p = air density (slugs/ft3) It was also explained in this chapter that the frontal area A is the frontal projection of the area and could be approximated simply by multiplying 0.85 times the width and the height of a rectangle that outlines the front of a vehicle when you view it from a direction normal to the front windshield. The 0.85 factor is to adjust for rounded corners, open space below the bumper, and so on. Typical drag coefficient values for sports cars are between 0.27 and 0.38, and for sedans the values are between 0.34 and 0.5.
a. What is the appropriate unit for Cd if the preceding equation is to be homogeneous in units? Show all steps of your work.
