Why do you need to apply a force in order to get the box to move?

2kg of refrigerant 134a undergoes a polytropic process in a piston-cylinder assembly from an initial state of saturated vapor at 2 bar to a final state of 12 bar, 80 degree c. a)determine the work for the process in kj. b)sketch the process on a p-v diagram.

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?

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