Item NG079002: The motion energy of a book sliding across a table is transformed into thermal energy, not into a force.

A girl shoves a book, and it slides across a table.  The book slows down and then stops.  As the book moves, the book and the table get a little bit warmer.  What happened to the motion energy (kinetic energy) of the book?

  1. It was transformed into a force but not into thermal energy.
  2. It was transformed into thermal energy but not into a force.
  3. It was transformed into both a force and thermal energy.
  4. It was used up and was not transformed into a force or thermal energy.