Answer:
The thermal conductivity of the insulated metal rod is [tex]202.92\,\frac{W}{m\cdot K}[/tex].
Explanation:
This is a situation of one-dimensional thermal conduction of a metal rod in a temperature gradient. The heat transfer rate through the metal rod is calculated by this expression:
[tex]\dot Q = \frac{k_{rod}\cdot A_{c, rod}}{L_{rod}}\cdot \Delta T[/tex]
Where:
[tex]\dot Q[/tex] - Heat transfer due to conduction, measured in watts.
[tex]L_{rod}[/tex] - Length of the metal rod, measured in meters.
[tex]A_{c,rod}[/tex] - Cross section area of the metal rod, measured in meters.
[tex]k_{rod}[/tex] - Thermal conductivity, measured in [tex]\frac{W}{m\cdot K}[/tex].
Let assume that heat conducted to melt some ice was transfered at constant rate, so that definition of power can be translated as:
[tex]\dot Q = \frac{Q}{\Delta t}[/tex]
Where Q is the latent heat required to melt the ice, whose formula is:
[tex]Q = m_{ice}\cdot L_{f}[/tex]
Where:
[tex]m_{ice}[/tex] - Mass of ice, measured in kilograms.
[tex]L_{f}[/tex] - Latent heat of fussion, measured in joules per gram.
The latent heat of fussion of water is equal to [tex]330000\,\frac{J}{g}[/tex]. Hence, the total heat received by the ice is:
[tex]Q = (6.15\,g)\cdot \left(330\,\frac{J}{g} \right)[/tex]
[tex]Q = 2029.5\,J[/tex]
Now, the heat transfer rate is:
[tex]\dot Q = \frac{2029.5\,J}{(10\,min)\cdot \left(60\,\frac{s}{min} \right)}[/tex]
[tex]\dot Q = 3.382\,W[/tex]
Turning to the thermal conduction equation, thermal conductivity is cleared and computed after replacing remaining variables: ([tex]L_{rod} = 0.75\,m[/tex], [tex]A_{c,rod} = 1.25\times 10^{-4}\,m^{2}[/tex], [tex]\Delta T = 100\,K[/tex], [tex]\dot Q = 3.382\,W[/tex])
[tex]\dot Q = \frac{k_{rod}\cdot A_{c, rod}}{L_{rod}}\cdot \Delta T[/tex]
[tex]k_{rod} = \frac{\dot Q \cdot L_{rod}}{A_{c,rod}\cdot \Delta T}[/tex]
[tex]k_{rod} = \frac{(3.382\,W)\cdot (0.75\,m)}{(1.25\times 10^{-4}\,m^{2})\cdot (100\,K)}[/tex]
[tex]k_{rod} = 202.92\,\frac{W}{m\cdot K}[/tex]
The thermal conductivity of the insulated metal rod is [tex]202.92\,\frac{W}{m\cdot K}[/tex].
