Which of these is true about convection? O A. It transfers thermal energy using currents.
O B. It can move thermal energy through empty space.
O C. It uses vibrations to move energy between particles.
O D. It causes substances to change state.

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.

How does an observation about an object differ from an inference about that object

Aforce of 100 newtons is used to move an object a distance of 15 meters with a power of 50 watts. find the work dine and the time it takes to do the work