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Homework Help: Accelarating on a curve please help soon

  1. Feb 28, 2010 #1

    reticpythons

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    1. The problem statement, all variables and given/known data
    A flat (unbanked) curve on a highway has a radius of 260 m. A car rounds the curve at a speed of 18.0 m/s . What is the minimum coefficient of friction that will prevent sliding?


    2. Relevant equations

    A= v2/R I got the acceleration but the problem does not give the mass for caluculating the normal force

    3. The attempt at a solution
    1.246 m/s is what I got for the acceleration after that I do not know what I should be doing.
     
    reticpythons, Feb 28, 2010
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  3. Feb 28, 2010 #2

    rl.bhat

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    Homework Helper

    Hi reticpythons, welcome to PF.
    The car rounds the curve due to the centripetal force provided by the frictional force.
    write down the expression for both and equate them to get the required result.
     
    rl.bhat, Feb 28, 2010
  4. Feb 28, 2010 #3

    reticpythons

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    the centripital force is v2/R but I can not think of what i need to equate it to Fnet= Fn-fk=ma but I do not have mass or I might be totally spacing something I should know but I am looking through my notes and can not find or think of anything
     
    reticpythons, Feb 28, 2010
  5. Feb 28, 2010 #4

    rl.bhat

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    Homework Helper

    Normal force is mg and frictional force is μ*mg.
    Centripetal force is m*v^2/r. Frictional force provides centripetal force to the car to go round the curve without skidding.
    Equate them to find μ.
     
    rl.bhat, Feb 28, 2010
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