The hot reservoir for a Carnot engine has a temperature of 926 K, while the cold reservoir has a temperature of 441 K. The heat input for this engine is 3730 J. The 441-K reservoir also serves as the hot reservoir for a second Carnot engine. This second engine uses the rejected heat of the first engine as input and extracts additional work from it. The rejected heat from the second engine goes into a reservoir that has a temperature of 191 K. Find the total work delivered by the two engines.
physics - drwls, Saturday, December 1, 2012 at 7:11pm
The efficiency of the first Carnot engine is
1 - (441/926) = 0.5238
The work out of that engine is 3730*0.5238 = 1954 J
The heat output of that engine is 3730-1954 = 1776 J. That heat is the input to the second engine. The second engine's efficiency is
1 - (191/441) = 0.5669. Its work output is
1776*0.5669 = 1007 J
Add the work outputs of the two engines for the final answer.