Wind Drag On A Car...
Estimate the drag force, in pounds, on a car with a coefficient
of drag of 0.32 and a frontal area of 25 square feet, traveling
through air at 55 mph. Then estimate the horsepower required to
maintain that speed.
DragForce = 1/2 * Cd * Density * Velocity Squared * Area
Power = Force * Velocity
First we must convert the parameters to a coherent system of units
so we can actually use the equations. Note the density of air is 1.293 kg/m^3
First convert speed to meters.sec
Then square feet to square meters...
Plug into the equation and get force in Newtons...
Then convert Newtons to pounds force...
Now calculate the horsepower...
Now the same calculation using Calchemy
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Last Updated 6/21/2009
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