(a) What is the best coefficient of performance for a heat pump that has a hot reservoir temperature of 60.0C and a cold reservoir temperature of 20.0C? - (b) How much heat transfer (in kcal) occurs into the warm environment if 3.60 x 107 J of work (10.0 kW - h) is put into it? (c) If the cost of this work input is 10/kW - h, how does its cost compare with the direct heat transfer achieved by burning natural gas at a cost of 87.0 cents per therm. (A therm is a common unit of energy for natural gas and equals 1.055 x 108 J.) cost of heat pump = 91.7 cost of natural gas X