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Webassign even my ta's didn't know what to do ? and im in intro to physics

  1. Feb 6, 2009 #1
    webassign even my ta's didn't know what to do... ???... and im in intro to physics

    1. The problem statement, all variables and given/known data
    A 33 ohm resistor is made from a coil of Cu wire whose total mass is 12g. (a)What is the diameter of the wire and (b) how long is it ? ( give you answer in m)



    2. Relevant equations
    one equation my ta tried to use was (R) = (resistivity) x (L/A)


    3. The attempt at a solution
    no idea... we cant figure out where to go because the equation has both length and radius (in the equation for A of the cross section of the wire) as variables... this is the only question left on my webassign and i have 30 mins left... please help
     
  2. jcsd
  3. Feb 6, 2009 #2

    Dick

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    Re: webassign even my ta's didn't know what to do... ???... and im in intro to physic

    There is a mass in the problem. There's a second equation that says mass=density*volume=density*length*area.
     
  4. Feb 6, 2009 #3
    Re: webassign even my ta's didn't know what to do... ???... and im in intro to physic

    Two equations, two unknowns. Solve:

    [tex]R=\rho \frac{L}{A}[/tex] and [tex]m=dV=dAL[/tex] where d is density and rho is resistivity
     
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