Problem with units for conduction rate?

In summary, the question asks to find the conduction rate through a copper slab with given dimensions and temperatures. The formula Pcond = Kc *A*(TH - TC)/L is used with a conductivity value of 401 W/m*k. The conversion from degrees Celsius to Kelvin does not affect the final answer. The answer in the back of the book is correct.
  • #1
L_landau
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Homework Statement


Consider the slab shown in Fig. 18-18. Suppose that L 25.0 cm, A 90.0 cm2, and the material is copper. If TH 125 C, TC 10.0 C, and a steady state is reached, find the conduction rate through the slab.

Homework Equations


Pcond = Kc *A*(TH - TC)/L
K = 401 W/m*k

The Attempt at a Solution


I'm converting degrees celsius to kelvin so that it cancels with the kelvin unit from the conductivity K and I'm getting an answer of 5774W but when I look here

http://www.chegg.com/homework-help/questions-and-answers/consider-slab-shown-figure-18-18-suppose-l-290-cm-850-cm2-material-copper-th-103-c-tc-80-c-q43179
and here
http://www.chegg.com/homework-help/questions-and-answers/consider-slab-shown-figure-18-18-suppose-l-250-cm-860-cm2-material-copper-th-124-q4982672

they are leaving the degrees in celsius. What's more, the answer in the back of my book matches these answers! How can an answer in celsius over kelvin make any sense!? Is the answer in the back of the book also wrong?!
 
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  • #2
When you subtract the two temperatures, the difference between the two temperatures is the same in the Celsius and Kelvin scales. Thus (per degree Kelvin) and (per degree Celsius) give the same answer.
 

Related to Problem with units for conduction rate?

1. What is conduction rate?

Conduction rate refers to the rate at which heat or electricity is transferred through a material. It is a measure of how quickly energy is passed from one molecule to another within a substance.

2. What are the units for conduction rate?

The units for conduction rate depend on the specific type of conduction being measured. For thermal conduction, the units are typically watts per meter-kelvin (W/mK) or BTU per hour-square foot-degree Fahrenheit (BTU/hr ft² °F). For electrical conduction, the units are typically amps per meter (A/m) or siemens per meter (S/m).

3. Why is it important to pay attention to units when measuring conduction rate?

Units are important in any scientific measurement because they provide a common language for communicating and comparing data. When measuring conduction rate, using the correct units ensures that the results are accurate and can be properly interpreted by other scientists.

4. What are some common mistakes with units when measuring conduction rate?

One common mistake is using different units for the same type of conduction. For example, using joules per second-meter-kelvin (J/s mK) instead of watts per meter-kelvin (W/mK) for thermal conduction. Another mistake is using units that are not compatible with the type of conduction being measured, such as using meters per second (m/s) for electrical conduction.

5. How can one convert between different units for conduction rate?

To convert between different units for conduction rate, you can use conversion factors or conversion equations. These can be found in scientific reference materials or online resources. It is important to make sure that the conversion is accurate and appropriate for the specific type of conduction being measured.

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