# PHY2004 example test problem involving heat and gases

**1. The problem statement, all variables and given/known data**

In order to determine the thermal conductivity of a material, one measures the heat flow through it. It is found that 1000 cal flow in 2 minutes through a 3-cm2 area that is 0.2 cm thick. The temperature difference is maintained at 90◦F. What is the k for this material (in cal/cm·s·◦C)?

Given Info:

Specific heat of water: c = 1cal/g·◦C

g = 9.80 m/s2

Density of water: ρw = 1 g/cm3

Density of air 1.20 kg/m3

Universal gas constant: R = 8.314 J/mole K

1atm=105 Pa

Heat of fusion for water: Hf = 80 cal/g

Heat of vaporization for water: Hv = 539 cal/g

**2. Relevant equations**

I had no idea how to even start this problem, and my tutor didn’t either. He said we weren’t using the right equations and we couldn’t find any in the text book

**3. The attempt at a solution**

Couldn’t even begin, but the answer to the problem is, 1.11 × 10^−2. I would like to know the equation used to get this and the steps

http://ift.tt/1kRnAw8

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