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Mercedes-Benz on a hill (friction, normal force) Please help

  1. Apr 24, 2009 #1
    A Mercedes-Benz 300SL (m = 1700 kg) is parked on a road that rises 20° above the horizontal.
    (a) What is the magnitude of the normal force?
    (b) What is the static frictional force that the ground exerts on the tires?


    2. Relevant equations
    FN=Wcos(theta)
    Wsin(theta)=Framp
    (at least that's what was given in lecutre)

    3. The attempt at a solution
    To find the weight using 1700kg*9.8, but when I plug that in, the computer program (gotta love these for homework assignments...:grumpy:) says no. I'm lost as to how to proceed.
    Help would be greatly appreciated.
     
  2. jcsd
  3. Apr 24, 2009 #2

    Cyosis

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    Homework Helper

    Your method seems to be correct so I would recommend posting the numerical value your calculation gave you so we can compare. When taking the cos/sin did you have your calculator on degrees or on radians? What is the amount of significant figures asked etc etc.
     
  4. Apr 24, 2009 #3
    I've got my calculator on degrees. The program didn't define any sig figs (it usually takes whatever is put in), and the units are given. Trying to find Newtons for both.

    1700*9.8=16660=W

    FN= 16660cos(20)=15655.27

    Framp=16660sin(20)=5698.05
     
  5. Apr 24, 2009 #4
    Nevermind about the silly program...it was my fingers missing numbers on my calc. The numbers that I gave in the reply were the right ones. Thank you so much though!
     
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