11. what is "energy efficiency" and how efficient is the human body?

our bodies are not 100% efficient at converting food energy into mechanical output. But at about 25% efficiency, we're surprisingly good considering that most cars are around 20%, and that an Iowa cornfield is only about 1.5% efficient at converting incoming sunlight into chemical storage.

Explanation:

our bodies are not 100% efficient at converting food energy into mechanical output. But at about 25% efficiency, we're surprisingly good considering that most cars are around 20%, and that an Iowa cornfield is only about 1.5% efficient at converting incoming sunlight into chemical storage.