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marine345
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Homework Statement
I working on this for a high school thesis. I am trying to find the power required to move a 7100 lb vehicle over a variety of scenarios, but am having trouble calculating the force of tractive resistance.
Homework Equations
I found what i thought was a pretty exhaustive equation for the force of tractive resistance:
FTR=mg[sin[itex]\alpha[/itex]+C0sgn(V)]+sgn(V)[mgC1+([itex]\rho[/itex]/2)CDAF]V2+ma
where:
C0=dimensionless coefficient of rolling resistance
[itex]\alpha[/itex]=the angle of the surface the vehicle is navigating
C1=Coefficient of rolling resistance while in motion, calculated by (when C0=0.01) C1=C0(V2/100)
[itex]\rho[/itex]=air density (lb/ft3
CD=drag coefficient
AF=frontal area of the vehicle (ft2)
V=velocity (fps)
g=32fps2
The Attempt at a Solution
For my first scenario, finding FTR when the vehicle is going 20mph in sand, I plugged in these numbers and got:
FTR=(7100)(32)[sin(0)+0.35]+[(7100)(32)(0.35(29.3/35))+(0.0718/2)(0.75)(22)](29.3)2=5.72299(10^7)
I used 32fps2 as the acceleration of gravity, 29.3fps as velocity because that would give me the answer in ft/lbs, and calculated C1=0.35(29.3/35) because I figured '100' would change based on C0. I also thought this number was astronomically large, especially since it would be multiplied by velocity to find the required power to meet the scenario requirements. I have also donr the same with several other scenarios, and gotten really big numbers
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