A 30 kg boy sitting on a 10 kg go-kart wants to travel down a hill of height 10 m, starting from rest. a. What is the initial potential energy of the boy and go-kart together?
b. What is their initial kinetic energy?

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).