You carve your and your sweetheart's initials in the trunk of a 3-meter tall tree, 1.5 meters above the ground. fifty years later you return, and on a romantic whim, you find your old carved heart. the tree has grown one meter taller per year. how high above ground are your initials?

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.