chemical to thermal mechanical to thermal mechanical to chemical chemical to mechanical
I gave my students this multiple choice question: A carpenter covered a piece of wood with a thin sheet of paper. He struck the covered piece of wood with a hammer. The impact left a small hole in the paper that smelled of smoke. Which kind of energy transfer did this event most likely demonstrate?

Only one answer is correct among these 4 choices:
- chemical to thermal
- mechanical to thermal
- mechanical to chemical
- chemical to mechanical

Could you tell me which one is correct?

mechanical to thermal