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Homework Help: Rolling as Translation and Rotation Combined

  1. Oct 21, 2009 #1
    1. The problem statement, all variables and given/known data
    An automobile traveling at 30.0 km/h has tires of 85.0 cm diameter.

    (b) If the car is brought to a stop uniformly in 15.0 complete turns of the tires (without skidding), what is the magnitude of the angular acceleration of the wheels?

    (In part a I found the angular speed to be 19.6 rad/s

    2. Relevant equations

    (w^2 - wi^2)/(2 * change in theta) ??

    3. The attempt at a solution

    -wi^2/(2 *(2* 15pi) = angular acceleration

    I'm super lost and would appreciate any help at all. I just need a pointer in the right direction!
  2. jcsd
  3. Oct 22, 2009 #2


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    Homework Helper

    Your formula is correct. Check your ωi.
  4. Oct 22, 2009 #3
    I know that my wi is correct though..
    Is there another way to solve this problem maybe?
  5. Oct 22, 2009 #4
    Well, would the answer 2.038rad/s^2 make sense?
    Because that's what I got for my answer but I wasn't expecting the acceleration to be that much slower than the speed
  6. Oct 22, 2009 #5


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    Homework Helper

    Your answer is correct.
  7. Oct 22, 2009 #6
    Ok thank you so much!
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