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

Homework Help: Energy transfer

  1. Aug 3, 2010 #1
    1. The problem statement, all variables and given/known data
    A block of material with a cross sectional area of 15cm^2 and length of 8cm is at hand. A temperature difference of 30degrees is established and maintained across the block. Find the rate of heat flow through it if the material is wood (K = 0.08Js-1m-1C-1)

    2. Relevant equations

    P = KA(change in T)/L

    3. The attempt at a solution
    P is watts. I converted area and length into meters.

    Everything is given, all i need to do is plug in the values. I did that and I get 4.5 Watts. The answer in the back of the book is 5.6W.

    Can someone do the calculation and confirm it with me? Either it's an error in the book or I'm missing something.

    THANKS! :smile:
  2. jcsd
  3. Aug 3, 2010 #2


    User Avatar
    Homework Helper

    I plugged the values exactly as given into my calculator, and I get an answer that differs from yours by a factor of 1000. I'd suggest double-checking your unit conversions.

    I really don't know where the 5.6W in the back of the book might have come from, unless there's something more to the problem - but I can't think of what that might be.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook