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View Poll Results: What is answer the following question?

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  • 6

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Thread: Help in pendulm problem please

  1. #1 Help in pendulm problem please 
    Junior Member
    Join Date
    Feb 2014
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    10
    i m not able to solve this problem so can someone help me please
    Q)A pendulum of length 2 m left at A When it reaches B,it loses 10% of its total energy due to air resistance. The velocity at B is:
    A)6 m/s
    B)1 m/s
    C)2 m/s
    D)8 m/s
    please help me
    Thnx in advance

    please reply fast
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  2. #2  
    Senior Member
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    Jan 2014
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    out there
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    306
    Not enough information to frame the problem.
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  3. #3  
    Junior Member
    Join Date
    Feb 2014
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    10
    ok i got ans as 6.332
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  4. #4  
    Senior Member
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    Jan 2014
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    out there
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    You assumed 10 for g, an initial height 2 m, and you calculate V at the bottom without considering the 10% loss of KE. That is why you got the incorrect 6.332
    Multiply the the PE by 0.9 and you will get exactly 6 when using 10 for g, height of 2 and V at bottom

    If you had used 9.81 for g the answer with a 10% loss would be 5.94 = 6, without the loss 6.26 again wrong.
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