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Nonuniform Circular Motion

  1. Mar 21, 2006 #1
    A 600 g steel block rotates on a steel table while attached to a 1.20 m-long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.30 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 60.0 N.

    If the block starts from rest, how many revolutions does it make before the tube breaks?

    [​IMG]


    I've done some calculations and have come up with:
    Tangential Acceleration: 1.287 m/s^2
    Omega: 9.13
    Period: 8.513 seconds

    plugged these numbers into Theta=((a)/(2*r))*(period)^2
    and got 38.953 rads, or 61.19 revolutions... which was wrong :mad:
     
  2. jcsd
  3. Mar 21, 2006 #2

    nrqed

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    I am assuming that you don't mean "period", you mean the total time it takes to reach the final omega?? (it does not make sense to talk about a period since the rotation is not at a constant omega). And I am guessing that you mean 6.119 revolutions.

    Can you just show how you got your tangential acceleration?
     
  4. Mar 21, 2006 #3
    Wow thanks, yeah you were right, it was actually a decimal over... 6.1 revolutions.
     
  5. Mar 21, 2006 #4

    nrqed

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    So, do you have the right answer now?
     
  6. Mar 21, 2006 #5
    yep, thanks
     
  7. Oct 14, 2006 #6
    how the heck are you getting that time total of 8.513?
     
  8. Oct 15, 2006 #7
    bump? Any help there?
     
  9. Oct 15, 2006 #8

    OlderDan

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    What do you think it should be?
     
  10. Oct 15, 2006 #9
    No idea, tried for hours, couldn't come up with that answer. I figured it would be something with omega and accel, but nothing computes.
     
  11. Oct 15, 2006 #10

    OlderDan

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    Perhaps because that answer i wrong. It does have something to do with acceleration, and omega if you choose to use that. What did you try?
     
    Last edited: Oct 15, 2006
  12. Oct 15, 2006 #11
    my final velocity was 10.95 m/s and I tried to divide by my accel
     
  13. Oct 15, 2006 #12

    OlderDan

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    Let's say that is correct. What did dividing by acceleration give you? Where do you go from there?
     
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