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Homework Help: Banked curve, car, friction problem

  1. Oct 6, 2003 #1
    Hi, I've been working on this problem for a while and i keep on getting same answer! Can someone please tell me what im doing wrong.

    PROBLEM:
    A circular curve is banked so that a car traveling with uniform speed rouding the curve usualy relys on friction to keep it from slipping to its left or right.
    What is the maximum velocity the car can maintain in order that the car does not move up the plane. (Answer in KM/HR).

    radius = 56.4m
    mass_of_car = 2.3kg
    angle = 34ยบ
    coefficient of kinetic friction = 0.41


    MY WORK:
    N=(cos34)(mg)=18.68
    Fp=(sin34)(mg)=12.6
    Fr=(N)(0.41)=7.66
    Fc=centripital force=mv^2/r

    so heres my final equation to get v:
    (m)(v^2)/(r) - Fr = Fp
    (2.3)(v^2)/56.4 - 7.66 = 12.6
    v = 22.28m/s = 82.08 km/hr

    82.08km/hr is soo unrealistic for 2.8kg car to bank such a turn.
    heck, even my puny vw golf cant even do it at 82.08km/hr

    i must be doing something wrong!

    help please.
    thanks
     
  2. jcsd
  3. Oct 6, 2003 #2
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