Which of the following is the dimensional formula of the quantity which is expressed as force per unit area? * MLT⁻²
ML⁻¹T⁻²
M⁻¹LT²
ML²T⁻²

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.