examples of two laws of thermodynamics?

Question

examples pf the two laws of thermodynamics in terms of some common everyday events

Answer 1

The first law is that energy is conserved. The second law is that at best, the entropy of a system remains constant. In practical terms what this means is that when you extract energy from a system, you lose a little to entropy (unless you do the energy extraction infinitely slowly or at absolute zero, both conditions are impossible in practical situations).

In a concrete example, when you ride a bicycle, you expend about 100 J of energy per kilometer (very roughly). However, not all of that energy goes into moving you up the hill or down the road. You lose some to friction with the wind, friction of the tires with the road, friction in the drive train, friction in your cardiovascular system which has to move your blood around faster, you respirate some of it away in the form of waste heat because not all of the energy created by burning ATP in your muscles gets converted to mechanical motion of the muscle.

If you added up all the energy you expended in these processes it would come to about 100 J per kilometer. But if you calculate theoretically how many joules it should have taken to move you that same distance, that number would be a small fraction of the total. The energy difference can be thought of in terms of increases in temperature of the environment, which you heated up by pedaling a bicycle down the road, and with that increase in temperature comes a gain in entropy, which satisfies the 2nd law.

If you had pedaled infinitely slowly then the efficiency would be unity, the temperature of the system wouldn't rise at all, and the entropy gain would be zero. Of course you wouldn't get anywhere.

The standard joke is that you can state the laws of thermodynamics as: can't win, can't lose, might as well not even try.

Answer 2

As soon as I saw this question I knew there were three Laws of Thermodynamics. I checked it out and, sure enough, there are three. The First Law states that energy is conserved. The Second Law states that heat flows from hot objects to cold objects. The Third Law states: No device is possible whose sole effect is to transform a given amount of heat completely into work (since the exhaust temperature would have to be at absolute zero, which is unobtainable.

Answer 3

energy converted, not destroyed or created. for example, you car producing heat as it burns the gasoline. turning on a light bulb and heat is produced.

Answer 4

Evolution has nothing to do with any of those things. Nobody is saying the universe created itself from nothing.