Question
(a) On a winter day, a certain house loses $5.00 \times 10^8 \textrm{ J}$ of heat to the outside (about 500,000 Btu). What is the total change in entropy due to this heat transfer alone, assuming an average indoor temperature of $21.0^\circ\textrm{C}$ and an average outdoor temperature of $5.00^\circ\textrm{C}$? (b) This large change in entropy implies a large amount of energy has become unavailable to do work. Where do we find more energy when such energy is lost to us?
1. $9.78 \times 10^4 \textrm{ J/K}$
2. Indirectly, energy comes from the sun, which is stored as fossil fuels that are burned, or which makes electrical energy via hydro, photovoltaic, etc.
Solution Video