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Question in momentum of inertia

  1. Jun 25, 2012 #1
    http://store2.up-00.com/June12/ScF29742.jpg [Broken]


    can please help me how I can find N1 and N2

    and I don't understand what mean by Speeeeed varies from above and below ? b]
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Jun 26, 2012 #2
    where are you ?
     
  4. Jun 26, 2012 #3

    NascentOxygen

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    Staff: Mentor

    I believe it means that the flywheel smoothing is not perfect, it does not iron the speed out to be a perfectly constant 430 RPM. Rather, it smooths it out so that as the flywheel rotates, its instantaneous angular velocity during every revolution varies from a few % less than [what equates to] 430 RPM to the same few % faster than [what would equate to] 430 RPM.

    430 RPM is the average (or mean) rotational speed.
     
  5. Jun 26, 2012 #4
    see the teacher said

    N1 = 430 + ( 0.02 X 430 ) = 438.6 rpm
    N2 = 430 - (0.02 X 430 ) = 421.4 rpm


    How is that please tell me
     
  6. Jun 26, 2012 #5

    NascentOxygen

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    0.02 is 2% and I think I explained the rest in post #2
     
  7. Jun 26, 2012 #6
    I know this 430 + ( 0.02)

    but why then multiply in 430 ??
     
  8. Jun 26, 2012 #7

    berkeman

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    That is how you calculate percent.

    1% of 100 kilograms is 0.01 * 100kg = 1kg.

    Does that make sense now?
     
  9. Jun 26, 2012 #8

    berkeman

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    Staff: Mentor

    And more like your problem,

    Adding 1% to the mass of 100kg:

    1.01 * 100kg = 100kg + 0.01 * 100kg = 101kg
     
  10. Jun 27, 2012 #9
    thaaaaaaaaaaaaaaaaaaaaank so so so so so much
     
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