Use the worked example above to help you solve this problem. An arctic explorer

Question

Use the worked example above to help you solve this problem. An arctic explorer builds a wooden shelter out of wooden planks that are 1.1 cm thick. To improve the insulation, he covers the shelter with a layer of ice 3.2 cm thick.

(a) Compute the R factors for the wooden planks and the ice.
Rwood = ANS = .11
Rice = ANS = .02

(b) If the temperature outside the shelter is -17.5°C and the temperature inside is 4.75°C, find the rate of energy loss through one of the walls, if the wall has dimensions 2.00 m by 2.00 m.
ANS = 684.615

(c) Find the temperature at the interface between the wood and the ice.
C

Rather than use ice to cover the wooden shelter, the explorer glues pressed cork with a thickness 0.500 cm to the outside of his wooden shelter. Find the new rate of energy loss through the same wall. (Note that kcork = 0.046 J/s · m · °C.)

Explanation / Answer

the energy loss by conduction is dQ/dt = (KA/L)T

here K = coefficient of conductivity ( K = 0.046 J/s.m .C ), A = area of the wall (A = 4 m^2) , L = thickness of the wooden shelter (0.500*10^-2 m ) and T = cange in temparature(T = 4.75 + 17.5)

therefore dQ/dt = (0.046*4/0.500*10^-2 )*22.25

                           = 818.8 J

the new rate of energy loss through the same wall is 818.8 J.

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