(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Ignoring air resistance is a large error when dealing with cars, especially when they are traveling at high speeds. Remember that air resistance depends on the speed squared F_ar=-Av^2.

A) draw a "FBD" for the car. show that the power required to keep a car going at a constant speed on a flat road against air resistance alone is proportional to the speed to the third power.

B)If your car consumes 20hp when traveling at a constant speed of 30mph. how much more power would it need to travel at a constant speed of 60mph under the same conditions?

2. Relevant equations

Not really sure what i should even start with for part A i used

Newtons second law and thats all i pretty much used so far

3. The attempt at a solution

A) For the free body diagram ill list the forces i included: Gravity(down), Normal force(up), Air resistance(left),Motor force=F(right)

so i can set F-F_ar=M*A (but it says the is traveling at a constant speed so i can just a=0 and then get

F=F_ar

So i think i did this part right but i don't know were to go from here to prove that the force is 3x the velocity

Any help would be appreciated -Thanks Tom

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# Homework Help: Air resistance

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