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Homework Help: Need Help Creating a Free Body Diagram of a Car on a Slope

  1. Jul 2, 2011 #1
    Hello. I have attached an image of a free body diagram of a car traveling up a ramp at 30 degrees. I was wondering if anyone can help me determine the sumation of forces in the X and Y direction.

    I understand that the forces in the Y-direction must be equal to zero or else the car will not stay on the ground. This is the formula I have come up with for this problem:

    u = coeff. of friction

    FN = mg / cos30

    Fu = u x FN

    F = force the car is moving under its own power

    Sum of Forces in Y direction: FN x cos30 - mg = 0

    Is this the correct equation for finding the forces in the Y direction?

    Sum of Forces in X direction: F - Fu - (mg x sin30) = ma

    Is this the correct equation for finding the forces in the X direction?

    Any help would be appreciated. Thank you!

    Attached Files:

  2. jcsd
  3. Jul 2, 2011 #2


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    welcome to pf!

    hello mjgarrin! welcome to pf! :smile:

    (have a mu: µ and a theta: θ and a degree: ° :wink:)

    first, your free body diagram is wrong, the mgcosθ is not a separate force and should not be there
    no, the FN x cos30° and the mg are not in the Y direction, are they? :redface:
    yes :smile:
  4. Jul 2, 2011 #3

    jack action

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    [PLAIN]http://hpwizard.com/images/hill-climbing.GIF [Broken]

    See http://hpwizard.com/car-performance.html" [Broken] for more info (At the bottom of the page --> Theory»»Longitudinal acceleration»»Accelerating»»Hill climbing)
    Last edited by a moderator: May 5, 2017
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