Heat flows from a reservoir at 373 K to a reservoir at 273 K through a 0.42-m copper [thermal conductivity 390 J/(s·m·C°)] rod with a cross-sectional area of 9.1x10 -4 m 2 (see the drawing). The heat then leaves the 273-K reservoir and enters a Carnot engine, which utilizes part of this heat to do work and rejects the remainder to a third reservoir at 173 K. How much of the heat leaving the 373-K reservoir is rendered unavailable for doing work in a period of 2.2 min?