The matter that makes up the car increases. The amount of useful energy decreases. The efficiency of the car increases. The amount of heat energy decreases.
I gave my students this multiple choice question: As a car burns fuel, a transformation from chemical to mechanical energy takes place. What is the most likely result of the fuel burning?

Only one answer is correct among these 4 choices:
- The matter that makes up the car increases.
- The amount of useful energy decreases.
- The efficiency of the car increases.
- The amount of heat energy decreases.

Could you tell me which one is correct?

The amount of useful energy decreases.