Over a period of time, fuel provides a car with energy $X$. Part of this energy becomes kinetic energy while the car speeds up. The remaining energy $Y$ is transferred away as thermal energy. What is the efficiency of the car?
- A$\frac{X}{X - Y}$
- B$\frac{Y}{X - Y}$
- C$\frac{X - Y}{X}$
- D$\frac{X - Y}{Y}$