Calculating Heat Flow Through a Block of Material

In summary, the problem involves finding the rate of heat flow through a block of wood with given dimensions and a temperature difference. Using the formula P = KA(change in T)/L, the rate of heat flow is calculated by plugging in the values and converting the units correctly. The answer in the back of the book may be incorrect, as the calculation results in a different value.
  • #1
mizzy
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Homework Statement


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)


Homework Equations



P = KA(change in T)/L

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:
 
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  • #2
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.
 

1. How is heat flow through a block of material calculated?

Heat flow through a block of material is calculated using the equation Q = (kAΔT)/d, where Q is the heat flow, k is the thermal conductivity of the material, A is the cross-sectional area of the block, ΔT is the temperature difference across the block, and d is the thickness of the block.

2. What is thermal conductivity and how does it affect heat flow?

Thermal conductivity is a measure of how well a material can conduct heat. Materials with higher thermal conductivity will allow for faster heat flow through a block, while materials with lower thermal conductivity will have slower heat flow.

3. How does the thickness of a block of material affect heat flow?

The thickness of a block of material directly affects heat flow. The thicker the block, the longer it will take for heat to transfer through it. This is because the thicker the block, the more distance the heat must travel through the material.

4. Can heat flow through a block of material be controlled?

Yes, heat flow through a block of material can be controlled by changing the temperature difference across the block or by changing the material used. Materials with higher thermal conductivity will allow for faster heat flow, while materials with lower thermal conductivity will have slower heat flow.

5. Are there any other factors that can affect heat flow through a block of material?

Yes, there are other factors that can affect heat flow through a block of material, such as the shape and size of the block, the material's density, and any insulating layers or barriers present. These factors can impact how quickly or slowly heat transfers through the block and should be taken into consideration when calculating heat flow.

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