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Homework Help: Work help i'm stuck and about to kill myself

  1. Dec 5, 2005 #1
    work help!!!!!!!! i'm stuck and about to kill myself

    A car at the Indianapolis-500 accelerates uniformly from the pit area, going from rest to 320 km/h in a semicircular arc with a radius of 192 m.

    Determine the tangential acceleration of the car when it is halfway through the turn, assuming constant acceleration.
    m/s^2(tangent to the path)
    (I know that the equation is equal to mv2/r but how do i set it up. what is the difference between tangent and toward the center.)

    Determine the radial acceleration at this time.
    m/s^2 (toward the center of the path)
    (It is rev/sec and multiply. i got 3.7m/s^2)

    If the curve were flat, what would the coefficient of static friction have to be between the tires and the roadbed to provide this acceleration with no slipping or skidding?

    (mu=fN I got all these other formulas and forces on the car and put them together, and i got .48 but it's wrong)
  2. jcsd
  3. Dec 5, 2005 #2


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    Staff Emeritus
    Science Advisor

    This might help.
    http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html, specifically http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html#req

    and this is a nice reference


    The tangential velocity is the linear velocity tangent (parallel) to the trajectory, which is perpendicular to the radial direction for a semi-circle.

    The key here is that the acceleration is uniform. The car starts with 0 velocity and reaches 320 km/h at the end of the semi-circle of radius 192 m, and it must travel a distance x = [itex]\pi[/itex]*192 m. Note that the angle through which the acceleration takes place is [itex]\pi[/itex] radians.
    Last edited by a moderator: Apr 21, 2017
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