Question: A carpenter rubs sandpaper on a wooden bench to make the bench smoother. The sandpaper will get warm as it is rubbed on the bench. As a result of the friction between the sandpaper and the bench, thermal energy is converted to

  Options: 
 A. chemical energy that is stored by the sandpaper.
 B. radiant energy that is transferred to the bench.
 C. potential energy that is stored by the wood.
 D. heat energy that is transferred to the air.
Answer: D