Which of the following correctly describes nuclear decay

An apple is falling from a tree. disregarding air resistance, which diagram shows the free-body diagram of the force or forces acting on the apple?

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.

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.