1. Find the energy transferred in 1 h by conduction through a concrete wall 1.6

Question

1. Find the energy transferred in 1 h by conduction through a concrete wall 1.6 m high, 3.05 m long, and 0.20 m thick if one side of the wall is held at 20°C and the other side is at 5°C.

2. A 40 g block of ice is cooled to -70°C and is then added to 600 g of water in an 80 g copper calorimeter at a temperature of 27°C. Determine the final temperature of the system consisting of the ice, water, and calorimeter. Remember that the ice must first warm to 0°C, melt, and then continue warming as water. The specific heat of ice is 0.500 cal/g ·°C = 2090 J/kg°C.

Explanation / Answer

Thermal conductivity of concrete

K=0.5 W/m-K

energy transferred is given by

E=KA*dT*t/L

E=0.5*(1.6*3.05)*(20-5)*(1*60*60)/0.2

E=658.8 KJ

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