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Rate of heat loss?

  1. Jan 7, 2006 #1
    A copper sphere of 8cm diameter is blackened and suspended from the ceiling by a fine thread in a room kept at 25 degrees C. The sphere is then heated to a temp of 147 degrees C.
    Calculate the net rate of heat loss by the sphere.

    Im not given any constants such as stefans or the emissivity of the body, so how can this be calculated?
     
  2. jcsd
  3. Jan 8, 2006 #2

    Tide

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    The sphere is copper (i.e. great thermal conductor) so you can assume its temperature is constant throughout its volume. Treat it as a blackbody (emissivity = 1) which allows you to calculate the power radiated per unit area as [itex]\sigma T^4[/itex].
     
  4. Jan 8, 2006 #3
    Thank You I'll try it out when i get up out of the scratcher!!!!!
     
  5. Jan 8, 2006 #4
    Is the Temperature the difference in the temperature or the temperature of the black body itself?
     
  6. Jan 8, 2006 #5

    Tide

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    It's the temperature of the object itself!
     
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