If an automobile had a 100% efficient engine transferring all of the fuel's energy to work, would the engine be warm to your touch? Would its exhaust heat the surrounding air? Would it vibrate? Would any of its fuel go unused?
There are really no 100% percent efficient machines, are there??
The exaust temp would be zero K. The engine would be at the same temperature it started at (probably O K, the exaust temperature)
It could not vibrate, that takes energy.
If an automobile had a 100% efficient engine, all the fuel's energy would be completely converted to work, meaning no energy would be lost in the form of waste heat or vibrations. In this scenario, the engine would not heat up significantly and would not be warm to the touch. However, it's important to note that this situation is not possible in reality due to various factors such as friction and combustion inefficiencies.
In a real-world scenario, no engine can achieve 100% efficiency. It's because energy is always lost in the form of waste heat and other losses, which is unavoidable. This waste heat is usually transferred through the exhaust system, which heats up the surrounding air. So, in a practical engine, the exhaust would indeed heat the surrounding air.
Additionally, engines also vibrate due to various factors such as rotational forces, combustion cycles, and imbalances. Even if an engine were designed to minimize vibrations, some level of vibration would still be present.
Lastly, in an ideal 100% efficient scenario, all the fuel's energy would be utilized and nothing would be wasted or unused. However, in real engines, there are always losses due to factors like incomplete combustion, friction, and inefficiencies in energy transfer.
In summary, while the concept of a 100% efficient engine is hypothetical, it helps us understand the limitations and losses present in real-world engines.