Susie (45kg) and troy (65 kg) are sitting 2 meters apart. they smile at each other. what is the gravitational force between them? a 4.9x10^8 n b 9.8x10^-8 n c 9.8x10^8 n d 4.9x10^-8 n

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.