What is the force of wind resistance on a sign attached to a vehicle?

[Taiki_Kazuma]

Okay, so here's the thing...

D=\frac{1}{2}*C_D*r*v^2*A

I need to find the Force pushing against a sign that is attached to a vehicle.

The area (A) of the sign is 60"X28" which is 42.672 m^2

The velocity (v) that the vehicle will be moving is roughly 80 miles per hour which converts to 35.7632 \frac{m}{s}

The next 2 I'm not sure about...

Air density (r) is 1.229 \frac{Kg}{m^3}?
and
C_D (Coefficeitn of friction) of this sign (which the broad side will be hitting the wind head on) is 1.28?

So I did all this calculation and got

42929 N which is 9651 lbs. That is a hell of a lot of force. I was wondering if I did all this correct...please let me know. Thanks

 

[krab]

The area (A) of the sign is 60"X28" which is 42.672 m^2

There's your error.

 

[haynewp]

I would expect it to be in the 150 to 200 lb range.