two students in a science classroom are debating about whether the tables are made of wood or plastic. as the teacher passes by, she suggests, use cell theory to find the truth. propose a scientific investigation to determine whether the tables are wooden or plastic. Include your hypothesis, what steps the students should take, and any materials they might need to carry out the produce.​

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.