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Angular momentum and change in velocity

  1. Oct 28, 2011 #1
    1. The problem statement, all variables and given/known data

    A turntable has a moment of inertia of 2.5 x 10-2 kg m2 and spins freely at 33.3 rev/min. A 0.25 kg ball of putty is dropped vertically on the turntable at a point 0.20 m from the center. What is the new angular speed of the system?

    a. 41 rev/min
    b. 24 rev/min
    c. 33 rev/min
    d. 27 rev/min

    2. Relevant equations


    3. The attempt at a solution

    i tried to do Iω=(I+mr)ω(final)
    i got 27 rev/min
    the real answer is supposed to be 24rev/min according to the answer key
  2. jcsd
  3. Oct 28, 2011 #2


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    Homework Helper

    Can you show the details of your calculation? We can't tell you what you did wrong if you don't show us your work!
  4. Oct 28, 2011 #3
    "i tried to do Iω=(I+mr)ω(final)"

    Careful, mr does not have same units as I.
  5. Oct 29, 2011 #4
    Yeah that was my error thanks!
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