Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    Science Advisor
    Homework Helper

    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


    User Avatar
    Science Advisor
    Homework Helper

    It's the temperature of the object itself!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Rate of heat loss?
  1. Heat loss in space (Replies: 8)

  2. The rate of heat loss (Replies: 3)