Which observation shows energy is conserved when a car converts chemical energy to motion?

• A. The mass of the car is greater than that of the gasoline.
• B. The energy in the gasoline was extracted from crude oil, which had more energy.
• C. Some of the energy of the gasoline is also converted to heat and sound energy.
• D. Not all car engines are equally efficient at this energy transformation.

Answer: (C)

Energy can’t be created or destroyed; it only changes form. In a car, the chemical energy stored in fuel is transformed into motion, but not all of it becomes kinetic energy. Some energy becomes heat in the engine and exhaust, and some becomes sound. When you add these energy outputs together with the energy used for motion, you recover the original amount of chemical energy, showing that energy is conserved through the transformation. This observation directly demonstrates energy accounting across forms. Statements about energy’s source or about engine efficiency don’t show the conservation in the same direct way, since they don’t track all the forms energy takes during the conversion.