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Homework Help: Required frictional force for a car to keep it from sliding off a curve.

  1. Nov 11, 2007 #1
    1. The problem statement, all variables and given/known data
    With what frictional force must the road push on a 1200 kg car if the driver exceeds the speed for which the curve was designed by deltav = 14km/hr?


    3. The attempt at a solution
    I actually have no clue where to begin with this question. Don't I need the radius to figure this out? On the previous problem i was asked to find the bank angle of a curve given radius and velocity and I used tan-1 [v^2/(gr)]. I don't believe that equation is relavent here though. Any advice as to what equations I should be using?
     
    Last edited: Nov 11, 2007
  2. jcsd
  3. Nov 11, 2007 #2
    There is no radius given?

    Is that exactly how the question is written? It seems kinda confusing
     
  4. Nov 11, 2007 #3
    Yup, that's all it says, other than answer in units of N at the end. Doesn't even say if it's a flat curve or banked.
     
  5. Nov 11, 2007 #4
    Now the question doesn't say to refer to the previous problem, but if it does it was If r = 51 m and v = 52 km/hr, what is theta? and i found that to be 22.646 degrees. Can we do anything with that information?
     
  6. Nov 11, 2007 #5
    AHAH! Well I decided to use the degree, radius and velocity from the previous 2 problems, found my force of the original speed that required no friction, added 14km/hr to it and found that force, then subtracted one from the other and that answer was correct. Would have been a whole lot simpler if they had just said "refer to the previous 2 problems to solve this one". Thanks anyways!
     
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