A 50-kg iron block and a 20-kg copper block, both initially at 80°C, are dropped into a la...

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. Thermal equilibrium is established after a while as a result of heat transfer between the blocks and the lake water. Determine thetotal entropy change for this process.