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Homework Help: Power generated by a rollerblader

  1. Feb 16, 2010 #1
    Jacinta is rollerblading along a straight flat road at a steady speed of 15m/s. The average force of rolling friction from the wheels is around 5N and the total air resistance force is around 55N.

    What is the power she is generating at this time?
     
  2. jcsd
  3. Feb 16, 2010 #2

    rock.freak667

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    Re: Energy

    So what do you think you need to do to get the power?
     
  4. Feb 16, 2010 #3
    Re: Energy

    well theres the formula p=w/t or p=fv
     
  5. Feb 16, 2010 #4

    rock.freak667

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    Re: Energy

    If you use P=Fv, what is the force she is exerting to move at constant speed?
     
  6. Feb 16, 2010 #5
    Re: Energy

    how do we know net force, we only know friction
     
  7. Feb 16, 2010 #6

    rock.freak667

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    Re: Energy

    the girl is moving in a straight line at constant speed. What does Newton's 2nd law say about her acceleration?
     
  8. Feb 16, 2010 #7
    Re: Energy

    so net force is 0?
     
  9. Feb 16, 2010 #8

    rock.freak667

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    Re: Energy

    Yes, so what is the force she is exerting?
     
  10. Feb 16, 2010 #9
    Re: Energy

    um..zero?
     
  11. Feb 16, 2010 #10

    rock.freak667

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    Re: Energy

    The force she is exerting minus the forces due to friction is zero.
     
  12. Feb 16, 2010 #11
    Re: Energy

    ohhh yeah! so that means she is also exerting 60N which makes her travel at constant speed! thankyou I get it now!
     
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