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Homework Help: Calculate revolution time

  1. Dec 12, 2012 #1
    1. The problem statement, all variables and given/known data

    Planet A (at X meters) completes 1 full rotation (Y sec). Planet A then shrinks to (X2 meters)
    What is its rotation speed now.
    Conservation of angular momentum

    2. Relevant equations

    3. The attempt at a solution
    I found how to reverse engineer the whole system but I'm unable to calculate w for a reduced radius.
  2. jcsd
  3. Dec 12, 2012 #2


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    Staff Emeritus
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    What's the formula for calculating angular momentum?
  4. Dec 12, 2012 #3
    I used V1 x R1 / R2 = V2 then used the velocity of V2 against the circ of Planet A's new radius to give the answer, yipee!!
  5. Dec 12, 2012 #4
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