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Homework Help: What is mu_min given radius 54m?

  1. Feb 11, 2010 #1
    What is mu_min given radius 54m?

    A)A car of mass M = 1400 kg traveling at 50.0 km/hour enters a banked turn covered with ice. The road is banked at an angle theta, and there is no friction between the road and the car's tires. http://session.masteringphysics.com/problemAsset/1011163/29/MLD_cm_7_a.jpg

    B)Now, suppose that the curve is level (theta = 0) and that the ice has melted, so that there is a coefficient of static friction mu between the road and the car's tires. (Part B figure) What is mu_min, the minimum value of the coefficient of static friction between the tires and the road required to prevent the car from slipping? Assume that the car's speed is still 50.0 km/hour and that the radius of the curve is given by the value you found for r in Part A.
    http://session.masteringphysics.com/problemAsset/1011163/29/MLD_cm_7_b.jpg


    I got A) r= 54.0 m because of r= v^2/[g*tan(theta)] given theta = 20

    I'm not sure what I need to do to get mu_min. Can someone please help me?
     
    Last edited: Feb 11, 2010
  2. jcsd
  3. Feb 11, 2010 #2
    You know the velocity, radius of the path, and mass of the car. The road applies a force to the car causing it to accelerate in a circular path. The force has magnitude,

    mu*m*g

    and equals the centripetal force, m*v^2/r
     
  4. Feb 11, 2010 #3
    thank you so much Spinnor!!
     
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