FunTrivia Homepage New Questions Unanswered Post a Question Goto Qn # Archives

# What is the name of a hypothetical reversible engine that is 100% efficient? Will we ever have such a working engine, and if not, why not?

Question #94310. Asked by rxbigdawg. (Apr 04 08 8:26 AM)

triviapaul

A perpetuum mobile.

"In thermodynamics, a reversible process, or reversible cycle if the process is cyclic, is a process that can be "reversed" by means of infinitesimal changes in some property of the system without loss or dissipation of energy."

http://en.wikipedia.org/wiki/Thermodynamic_reversibility

"Carnot realised that in reality it is not possible to build a thermodynamically reversible engine, so real heat engines are less efficient than indicated by Equation."

http://en.wikipedia.org/wiki/Carnot_heat_engine

"The term perpetual motion, taken literally, refers to movement that goes on forever. However, perpetual motion usually refers to a device or system that delivers more energy than was put into it. Such a device or system would be in violation of the law of conservation of energy, which states that energy can never be created or destroyed, and is therefore deemed impossible by the laws of physics."

http://en.wikipedia.org/wiki/Perpetual_motion

 Apr 04 08, 8:42 AM
gentlegiant17

The Carnot engine: http://en.wikipedia.org/wiki/Carnot_heat_engine

A realization of the Carnot engine: http://www.shermanlab.com/xmwang/myGUI/CarnotG.html

 Apr 04 08, 8:48 AM
Baloo55th

The things people forget about perpetual motion machines are: 1. Friction - even if you use PTFE and slipperier substances - which nibbles away at your efficiency; 2. You cannot get any useful work out of them - if you try, you lower the energy level just as you do in a battery, and batteries are far easier to use (and are used to power most perpetual motion machines that are 'demonstrated'.
Source: New Scientist over many years. One columnist, the author of the Ariadne page, actually took a PM machine around to several scientific conferences and meetings and no-one seemed able to explain it. He could, of course, but I don't know how he'd fiddled it.

 Apr 04 08, 1:24 PM
MonkeyOnALeash

The answer is this: Conservation of Energy. Nothing more. It CAN NOT be done. It defies Newtonian Laws.

 Apr 04 08, 1:56 PM

### Other Similar Questions & Answers

 How much fuel does a car use to start the engine? That is, how long does it have to idle before it would have been more efficient to switch the engine off and wait?

### Suggested Related FunTrivia Quizzes - 90,000 currently online

1 'Working'
 The TV show 'Working'.
W Very Difficult
10 Q
equinom
Apr 06 00
459 plays
2 The As Have it
 The ayes have it. All these questions have to do with places that not only start with 'A' but also end with 'a'.
Alphabetical Places Average
10 Q
minch
Aug 15 00
6690 plays
3 That's Not Their Name
 Throughout history, an extraordinary number of famous and infamous people have acted under false names. Simply choose the real name of each person in the question.
Nicknames & Aliases Tough
10 Q
conbreking
Nov 11 09
1071 plays

"Ask FunTrivia" is for entertainment purposes only, and answers offered are unverified and unchecked by FunTrivia. We cannot guarantee the accuracy or veracity of ANY statement posted. Feel free to post an updated response if you feel that an answer is inadequate or incorrect. Please thoroughly research items where accuracy is important to you using multiple reliable sources. By accessing our website, you agree to be bound by our terms of service.