A minivan has a 125horsepower engine with a maximum efficien

A minivan has a 125-horsepower engine with a maximum efficiency of 85%. Determine the maximum speed of the van on level ground with no head wind if its projected area is 30 sq. ft and its drag coefficient is 0.6. If there is a 30 mph head wind how does this answer change?

Solution

GIVEN-->   

TO FIND--> MAXIMUM SPEED OF VAN WITH NO HEAD WIND Vmax = ? AND EFFECT OF Vhead ON THIS ANSWER.

SOLUTION-->

BY FORMULA, Vmax = [2 x Pactual / (c x D x A)]^1/3

BY SUBSTITUTING VALUES IN ABOVE FORMULA--

Vmax = [2 x 79262.5 / (0.6 x 1.25 x 2.79)]^1/3 = [158525 / 2.0925] ^1/3 = 75758.66 ^1/3 = 42.15 mps = 94.3 MPH

MAXIMUM SPEED Vmax = 94.3 MPH (ANSWER)

FOR A HEADWIND OF 30 MPH THE MAX SPEED Vmax WILL REDUCE BY 30, THAT IS Vmax=94.3 - 30= 64.3

REDUCED MAX SPEED Vmax = 64.3 MPH (ANSWER)