Suppose that you exert 350 N horizontally on a 50-kg crate on a factory floor, where friction between the crate and the floor is 150 N. What is the acceleration of the crate?

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.