The average kinetic energy of a molecule in air at room temperature of 20$$^\circ$$C

There are two identical containers C$$_1$$ and C$$_2$$ containing to identical gases. Gas in C$$_1$$ is reduced to half of its original volume adiabatically, while the gas in container C$$_2$$ is also reduced to half of its initial volume isothermally. Find the ratio of final pressure in these containers. ($$\gamma$$ be the adiabatic constant).

In which mode of transmission, the heat waves travel along straight line with the speed of light?

Consider a compound slab consisting of two different materials having equal lengths, thickness and thermal conductivities K and 2K respectively. The equivalent thermal conductivity of the slab is