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Homework Help: Radial component of linear acceleration

  1. Mar 4, 2009 #1
    1. The problem statement, all variables and given/known data

    A 66-cm-diameter wheel accelerates uniformly about its center from 120 rpm to 260 rpm rpm in 4.9 s.

    2. Relevant equations

    [itex]a_t = r\alpha [/itex]
    [itex]a_c= r\omega^2 [/itex]
    [itex]a= a_r+a_t [/itex]

    3. The attempt at a solution

    I have discovered that:
    [itex]\alpha = 3.0 \frac{rad}{s^2} [/itex]
    [itex]a_t = 0.99/frac{m}{s^2} [/itex]

    I have tried using Pythagoras's theorem to solve for [itex]a_r [/itex], but that value does not work. What am I doing wrong?
  2. jcsd
  3. Mar 4, 2009 #2
    Oh, and I am using Mastering Physics and only have one submission left, so I had better make it count!
  4. Mar 4, 2009 #3
    Anyone have an idea for this one?
  5. Mar 4, 2009 #4


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    Homework Helper

    What is the question?

    Have you considered the rotational analogues to linear kinematic motion?

  6. Mar 4, 2009 #5
    it asks for the radial component of acceleration
  7. Mar 4, 2009 #6


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    Homework Helper

    At what point?

    a = ω²r

    So that means it is simply ω dependent.

    Are you sure they don't want α - angular acceleration?
  8. Mar 4, 2009 #7
    Well I've tried that and that value didn't work. The time limit is over I took a hit on that one. The answer they resulted in was 110 m/s. Whoa.
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