. A ruler is dropped from rest in an activity designed to determine the reaction time of physics student, Kathy Klutz. At the start, the bottom of the ruler is between Kathy’s fingertips, and she catches the ruler at the 24 cm mark. Calculate Kathy’s reaction time.

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.