Aplanet orbits a star along an elliptical path systems. in which of the following systems does the total mechanical energy of the system remain constant? a. the open system containing the planet b. the open system containing the planet and the star. c. the closed system containing the planet. d. the closed system containing the planet and the star

Refrigerant-134a flows through a carnot heat pump cycle at 0.5 kg/s. it is known that the maximum absolute temperature in the cycle is 1.1 times the minimum absolute temperature, and the net power input to the cycle is 2.5 kw. if the refrigerant changes from a saturated vapor to a saturated liquid during the heat rejection process, determine the maximum magnitude of the enthalpy of vaporization for this process in kj/kg (with 3 significant figures).