8-44 A 50-kg iron block and a 20-kg copper block, both

initially at 80°C, are dropped into a large lake at 15°C. Ther-

mal equilibrium is established after a while as a result of heat

transfer between the blocks and the lake water. Assuming the

surroundings to be at 20°C, determine the amount of work that

could have been produced if the entire process were executed

in a reversible manner.