A layer of insulating material with thermal conductivity K is placed on a layer of another material of thermal conductivity 2K. The layers have equal thickness. What is the effective thermal conductivity of the composite sheet?

The thermal conductivity of concrete is 0.8 W/mK and the thermal conductivity of wood is 0.1 W/mK. How thick would a solid concrete wall have to be in order to have the same rate of flow through it as an 8-cm thick wall made of solid wood? (Assume both walls have the same surface area.)
 

A window glass 0.50-cm thick has dimensions of 3.0 m by 1.5 m. If the outside temperature is -10°C and the inside temperature is 20°C, how much heat flows through the window in one hour by conduction only?

A sample of an ideal gas is in a tank of constant volume. The sample gains heat energy and its temperature changes from 300 K to 900 K.

If is the average speed of the gas molecules before absorption of heat and v₂ the average speed after absorption of heat, what is the ratio v₂/v₁ ?

In an electric furnace used for refining steel, the temperature is monitored by measuring the radiant power emitted through a small hole of area 0.5 cm². The furnace acts like a blackbody radiator. If it is to be maintained at a temperature of 16500C, at what level should the power radiated through the hole be maintained?