A supersonic jet is 7,800 kilometers east of U. S. airspace. If the jet flies at a constant velocity of 1,300 kilometers per hour to the west, how much time will it take the jet to fly
one-third of the way to U. S. airspace?

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.