In an engine, fuel and oxygen chemically react and release energy. What happens to the energy NOT used by the engine?
A.
It has been destroyed.
B.
It is lost in the form of heat and sound.
C.
It remains stored in the chemical bonds of the fuel.
D.
It is converted into methane.
B. It is lost in the form of heat and sound.
B. It is lost in the form of heat and sound.
The correct answer is B. It is lost in the form of heat and sound.
When fuel and oxygen chemically react inside an engine, they release energy in the form of heat and sound. This energy is mainly used to do useful work, such as powering the vehicle or generating electricity. However, not all of the released energy can be effectively converted into useful work. Some of it is lost as waste energy in the form of heat and sound.
The process of converting fuel into useful work is not 100% efficient. In an internal combustion engine, for example, only a certain percentage of the energy released from the fuel is converted into mechanical energy. The rest is dissipated as waste energy, primarily in the form of heat expelled through the exhaust system and sound produced by the engine.
This waste energy is referred to as "rejected heat" or "exhaust heat." It cannot be reused or converted back into useful work. It simply dissipates into the surrounding environment. That's why engines need mechanisms to cool down, such as radiators, to prevent overheating.