Why is a perfect heat engine Impossible?

Why is it impossible for a heat engine to be completely efficient?

It is impossible for heat engines to achieve 100% thermal efficiency () according to the Second law of thermodynamics. This is impossible because some waste heat is always produced produced in a heat engine, shown in Figure 1 by the term.

Why is it impossible to invent a perfect engine?

No matter how good of an engineer you are, you can’t invent a perfect engine. Why? It’s because of an energy crisis that pervades our universe. And it’s caused by entropy and the second law of thermodynamics.

Why is it impossible to create a 100% efficient machine?

Explanation: No machine is free from the effects of gravity, and even with wonderful lubrication, friction always exists. The energy a machine produces is always less than the energy put into it (energy input). … That is why 100% efficiency in machines shall not be possible.

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Why is Carnot engine Impossible?

No engine has been built using the cycle named in honor of Carnot because two parts of the cycle require total insulation. And two require conduction with one of either the hot or the cold sinks.

Why can a heat engine never be 100 efficient?

A heat engine is considered to be 100% efficient if only all the heat is converted into useful work or mechanical energy. Since heat engines cannot convert all the heat energy into mechanical energy, their efficiency can never be 100%.

Why is the efficiency of heat engine always less than unity?

Because according to Second law of thermodynamics ( KELVIN- PLANK STATEMENT ) some part of input energy always goes into the sink i.e low temperature reservoir and gets wasted. ….. The efficiency of a real engine is always less than that of a Carnot engine.

Why is it impossible to construct an engine that does nothing but convert heat to useful work?

You cannot construct an engine that does nothing but convert heat to useful work. … This version of the 2nd law implies that whenever energy is converted from heat to another form (e.g. heat to electric current) not all of the heat is available. Some must be lost and dumped into the environment.

How entropy is a measure of unavailable energy?

entropy, the measure of a system’s thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system.

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Why is the efficiency of a real life machine always less than 100 Give two reasons?

The percentage of the work input that becomes work output is the efficiency of a machine. Because there is always some friction, the efficiency of any machine is always less than 100 percent.

Why is the efficiency of a dynamo less than 100 %?

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work). The output work is always less than the input work because some of the input work is used to overcome friction. Therefore, efficiency is always less than 100 percent.