Question

The drag coefficient for a newly designed hybrid car is predicted to be 0.21. the cross-sectional area of the car is 30 ft2. determine the aerodynamic drag on the car when it is driven through still air at 55 mph.

Answer 1

Drag, D = 1/2*Drag coefficient*density of air*velocity^2*Frontal area

Where,
Density of air ≈ 1.225 kg/m^3
Velocity = 55 mph = 24.5872 m/s
Drag coefficient = 0.21
Frontal area = 30 ft^2 = 2.78709 m^2

Substituting;
D = 0.5*0.21*1.225*24.5872^2*2.78709 = 216.72 N