Every second, the sun converts 4 million tons of matter to energy. how long will it take the sun to reduce its mass by 1% (the mass of the sun is 2 × 1030 kg)? compare your answer with the lifetime of the sun so far.

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.