The air resistance to the motion of a vehicle is something important that engineers inve...

The air resistance to the motion of a vehicle is something important that engineers investigate. As you may also know, the drag force acting on a car is determined experimentally by placing the car in a wind tunnel. For a given car, the experimental data is generally represented by a single coefficient that is called the drag coefficient. It is given by the following relationship:

where

C_d = drag coefficient

F_d = measured drag force (lb)

r = air density (slugs /ft3)

V = air speed inside the wind tunnel (ft /s)

A = frontal area of the car (ft²)

What is the appropriate unit for C_d if the preceding equation is to be homogeneous in units? Show all steps of your work.