To store stacks of clean plates, a cafeteria uses a closed cart with a spring-loaded shelf inside. Customers can take plates off the stack one at a time through a hole in the top. A stack of plates compresses the spring 0.40 m. The spring constant is 240 N/m. What is the elastic potential energy of the spring?

If you touch a hot light bulb and get burned, that is an example of a. radiation b. convection c. conduction

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.

What is the force that opposes motion and works against the downward pull? a) friction b) gravity c) weight d) acceleration