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Homework Help: Uniform circular motion of a particle

  1. Sep 17, 2008 #1
    1. The problem statement, all variables and given/known data
    A particle is moving at a constant speed around a circle of radius 1.5 meters, and it completes 4 revolutions in 6 seconds.
    a) What is its speed?
    b) What is its radial acceleration?
    c) In which direction does ar point?
    d) What is it tangential acceleration, at?

    2. Relevant equations
    T=2pie times r/v
    at= derivative of v/t
    ar = -v2/r
    ac = ar + at

    3. The attempt at a solution
    answer: 2pie
    v=6.28 m/s

    ar = -v2/r
    ar = 39.43/1.5
    ar = 26.29 m/s2

    c. I am not sure how to get the direction.

    d. ac= ar + at
    26.29 = 26.29 + at
    at = 0???
  2. jcsd
  3. Sep 17, 2008 #2
    think about what would happen if it accelerated constantly tangentially, and describe that motion, and see if it fits with your problem
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