Two electrons are separated by a distance r in the x-direction. Assuming the electron spins are both pointing in the y-direction, determine the ratio of the magnetic interaction force between the electrons to the electric force between the electrons.

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.