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Homework Help: Banked curve with friction, but no angle

  1. Oct 23, 2013 #1
    1. The problem statement, all variables and given/known data
    A banked curve has been designed so that it is safest for a vehicle going 70 mph. The topography of the land restricts the radius of the road to 300m. Assume mu(static friction) is 0.80 and mu(kinetic friction) is 0.60.
    A 5512 lb vehicle travels with a speed of 60 mph on the curve.
    1. Calculate the force that the road exerts on the vehicle.
    2. Calculate the friction on the tires.

    2. Relevant equations
    Centripetal acceleration=v^2/r

    3. The attempt at a solution

    converted all mph's given to m/s and converted weight in lbs to N.
    tried to find the angle by:


    I came up with 19.45 degrees. This just doesn't seem right, that's an awfully steep bank.
    The rest I'm stumped about.
  2. jcsd
  3. Oct 23, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    How did you arrive at this? Note that the units do not match: The left side is an acceleration, while the right is a force.
  4. Oct 30, 2013 #3
    I was wrong in that angle. I found the correct angle by assuming no friction, solving the y force for Fn and substituting it in the x force equation. This gave me theta.
    Then, after figuring out the x y axis could be rotated to go with the Fn on the car, solved like any other incline plane problem.
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