Which wall loses thermal energy more quickly, thick or thin?

The rate of heat conduction depends on how far heat has to travel (L), as described below:

ΔQ/Δt = -kAΔT/L

(This formula says that the heat transfer rate is inversely proportional to the distance heat has to travel.)

This model has two situations for you to compare. On the left are two separate heat sources with a constant temperature. On the right are two separate objects with a thermometer that measures how much heat has been conducted. The upper test piece is twice as long as the lower one. Both are made of the same material. This would be like a thick wall compared to a thin one.

  1. Run the model and note the temperatures measured by the two thermometers.
  2. Turn the graph on to watch the changes of the temperatures.
  3. Use the buttons at the upper-right corner of the graph window to rescale the curves if necessary.

After you observe the model, answer the questions in your workbook.



Graph: On Off     Grid: On Off