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Homework Help: Relative Speed

  1. Jan 24, 2010 #1
    1. The problem statement, all variables and given/known data
    A tire 0.319 m in radius rotates at a constant
    rate of 98.4 rev/min.
    Find the speed (relative to the tire’s axle)
    of a small stone lodged in the tread on the
    outer edge of the tire.
    Answer in units of m/s.

    Find the acceleration of the stone.
    Answer in units of m/s2.

    2. Relevant equations

    ac= v2/r

    3. The attempt at a solution
    I basically solved for the velocity of the tire which is 197.22 m/s
    how do you find the relative speed ?? If you could find the velocity I would be able to solve for the acceleration. Thank you
  2. jcsd
  3. Jan 25, 2010 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    You are calculating the tangential speed of a point on the outer surface of the tire. How does that compare to the speed of the stone?

    Check your units. Your answer is not correct. (You are given the rotational speed in revolutions per minute, not seconds).

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