Suppose you have two black square plates, each at the same temperature, that are placed face to face with a small gap between them. They are both perfectly black and so absorb all electromagnetic radiation incident upon them but suppose one of the plates is emitting twice the radiation of the other. Explain why this would violate the second law of thermodynamics.

=force × distance a. work b. velocity c. pressure d. momentum

What is the angular momentum of the bar about the axle?

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.