A wheel has an angular speed of 54 rev/s when it experiences a constant angular acceleration of 64 rev/s2 which causes it to spin FASTER. During this time the wheel completes 81 rev. Determine how long the wheel was experiencing this angular acceleration. Express your answer using appropriate mks units.

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).