Answer to Question #45942 in Molecular Physics | Thermodynamics for Azmiah

Question

Tony is driving across the outback in the middle of the night. He finds that he is running
out of petrol and might not make it to the next town. He tells Katie, his passenger, that he’s
going to turn off the headlights in order to save fuel. She tells him this is nonsense; the lights
are powered with electricity, not petrol. Who is right? Discuss.

Answer 1

The lighting is powered from the battery. However, the battery is charged by a generator which is connected with the transmission of the car. According to the law of conservation of energy the energy that will spend on the light obtained from the fuel burned by car. So this amount of energy would not used for motion. In this case, not using of light is more frugally. But in other hand if we will not use this energy (will not use light) generator would still work, and energy losses are reduced insignificant or even stay the same.
If Tony will remove generator it may help, but when generator is not removed it’s better to use light.