The primary coil of a transformer has 60 turns. It is connected to an AC power supply with an effective voltage of 120V. Calculate the number of turns on the secondary coil needed to produce 45V in the secondary circuit.

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.