1. Think about friction. A book sliding across a level table comes to a stop. Because systems always go towards configurations of higher entropy, the final stopped state must have higher entropy than the preceding moving state. Can you explain the reason for this in terms of molecular motion? Explain why it would be extremely improbable for the book to subsequently slide back to where it started from.
2. When a book slides across a table and comes to a stop, both systems (i.e., the book and the table top) get slightly warmer as a result of the friction, so the internal energy of both systems increases. How can this happen if energy is conserved?