Avery long two-wire transmission line, each wire of radius a and separated by a distance d, is supported at a height h above a flat conducting ground. assuming both d and h to be much larger than a, find the capacitance per unit length of the line.

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.