Q & A: if an automobile had a 100% efficiency engine,would it be warm to your touch?

Question by joy_blue03: if an automobile had a 100% efficiency engine,would it be warm to your touch?
would its exhaust heat the surrounding air?would it make any noise?would it vibrate?woild any of its fuel go unused?Explain.

Best answer:

Answer by rkalch

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6 Responses to Q & A: if an automobile had a 100% efficiency engine,would it be warm to your touch?

  1. jhstha

    ??? What is this question about? Presuming 100% efficiency would exist, (you’d get the Nobel-prize already for 40% efficiency), we wouldn’t hear nor smell nor feel that machine, because no energy would be “wasted” on e.g. moving other parts (=noise), no oil or fuel would be licking (=loss of energy, would NOT be 100%), no heat would exhaust (also loss of energy), no vibration would take place (again moving unnecessary parts)
    Besides, If we had the knowledge for 100% efficiency, we had the fusion (something like an artificial sun on a very small scale), because only that is close to 100%.

  2. n317537

    I’m guessing but I would say no. Heat is energy and cold is absence of energy. If your engine was hot it would be loosing energy. If it did any of the other things it would be loosing or wasting energy.

  3. Tony

    It would not have an exhaust, exude heat and it would not vibrate or make noise, for those things would take away from it’s efficiency, they are wasted energy, so if it was 100% efficient, it would not have any of those.

    Interesting enough, you cannot have a 100% efficient automobile engine, but you can have a heat pump, rated at 13 SEER, which pumps 13 times more energy than it uses, creating an energy differential.

    It is not energy that is needed to do work, it is energy differential.

  4. Tekguy

    Well, heat is wasted energy, and noise is made up of vibrations – motion, so that is also wasted energy. And – hey are you really interested in this, or is this a cynical attempt to avoid reading your physics text?

  5. Kes

    That’s a very interesting question. If you could feel the heat of the engine it must be losing energy not being used to propel the car and can not be 100% efficient. However, an automobile engine (that burns fuel) is a so called heat engine and must produce waste heat in the process. We can collect energy from a hydrostatic dam using a water turbine but the water can never fall further than from the surface of the dam to the surface of the sea (and is usually much less for practical purposes) even though the oceans are very deep (seven miles deep at the Mariana trench!). In like manner a heat engine can only operate between the maximum temperature of the combusted fuel and atmospheric temperature (or the temperature of cooling water from the ocean?). It must discharge waste heat at or above the temperature of its environment and is lucky to be even 20 or 30% efficient. The temperature of the car’s tailpipe is well above ambient temperature. If the heat engine could discharge to absolute zero temperature it might approach 100% efficiency. The discharge temperature is called a heat sink. But that would be like the water turbine discharging to the bottom of the sea. It would take a lot of work to create the “hole” in the sea to pour the dam water into and the turbine which would have to be at the bottom of the hole. Hope that helps a little.

  6. DK

    A 100% efficiency means that the engine does not generate heat, no noise, …. This does not neceserily mean that it is hot or cold to the touch. The automobile’s temperature will be the same as that of it’s environment. Now, if your body temperature (37 deg celcius) is higher than that of the environment then the car will feel cold. Otherwise it will feel warm.

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