A 2.20kg pendulum starts from a height of 5.00m . It swings back and forth through one whole oscillation but only returns to a maximum height of 4.75m . How much negative work was done on the pendulum during the first entire oscillation?

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.