physicsheat
posted by lisa .
a piece of glass is 6mm thick and the coefficient of thermal conductivity of this glass is K=0.75Wm^1K^1.
if we add a 2nd identical piece of glass separated by an airgap of 5cm, the total thermal conduction will be reduced.
what is the ratio of heat transfer by conduction for the double pane to the single case.
K of air =0.023W m^1K^1

Add the thermal resistances of the two glass slabs and the air gap. The conductance is the reciprocal of the resistance. Are you sure the air gap is 6 cm and not 6 mm? With a gap that large, you are likely to get convection currents in the gap.
Thermal Resistance of one slab of glass:
R1 = W1/K1
Thermal Resistance of two slabs of glass with gap = Wair:
R2 = 2W1/K1+ Wair/Kair
where Wair is the air gap and kair is the termal conductivity of glass.
What you want is the ratio R1/R2 
what is W1 and K1?
so is Wair=thermal conductivity of air gap
and Kair=thermal conductivity of glass? 
W1 is the width of the glass slabs. They say it is 0.6 cm.
K1 is the thermal conductivity of the glass. Yes to your other questions.
Both W's should be in meters since the units of K contain m^1, but the answer to your question will be a dimensionless ratio anyway
Respond to this Question
Similar Questions

Physics
A windowpane is half a centimeter thick and has an area of 1.0 m2. The temperature difference between the inside and outside surfaces of the pane is 15° C. What is the rate of heat flow through this window? 
Physics
The temperature difference in and outside an electric oven is 150oC glass fitted on the door has thickness and area of 0.2cm and 300cm2 respectively. if thermal conductivity of glass is 0.84Js1m1K1 then how much heat will be lost … 
physics
A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.30 m × 1.72 m. On a certain day, the indoor temperature is 26°C and the outdoor temperature is 0°C. (Assume the thermal conductivity of the glass is 0.8 J/s · … 
physics
A large container is separated into two halves by a 2.0 cm thick glass divider. The area of the divider is 0.25 m^2 and the thermal conductivity of glass is 0.90W/m•K. Each side is filled with 30 kg of water, specific heat 4180 J/kg•K, … 
physics
A large container is separated into two halves by a 2.0 cm thick glass divider. The area of the divider is 0.25 m^2 and the thermal conductivity of glass is 0.90W/m•K. Each side is filled with 30 kg of water, specific heat 4180 J/kg•K, … 
physics
A large container is separated into two halves by a 2.0 cm thick glass divider. The area of the divider is 0.25 m^2 and the thermal conductivity of glass is 0.90W/m•K. Each side is filled with 30 kg of water, specific heat 4180 J/kg•K, … 
Physics
Use the exact values you enter in previous answer(s) to make later calculation(s). Energyefficient windows are constructed with two panes of glass separated by an air gap (see figure below). In a typical window of this type, the air … 
physics
A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.30 m × 2.22 m. On a certain day, the indoor temperature is 22°C and the outdoor temperature is 0°C. (Assume the thermal conductivity of the glass is 0.8 J/s · … 
Physics
A piece of glass has a temperature of 83.0 °C. Liquid that has a temperature of 43.0 °C is poured over the glass, completely covering it, and the temperature at equilibrium is 59.0 °C. The mass of the glass and the liquid is the … 
physics
A piece of glass has a temperature of 76.0 °C. Liquid that has a temperature of 40.0 °C is poured over the glass, completely covering it, and the temperature at equilibrium is 54.0 °C. The mass of the glass and the liquid is the …