×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Question about 1st and 2nd law

Question about 1st and 2nd law

Question about 1st and 2nd law

(OP)
Theoretically, if the 2nd law is broken, doesn't that automatically break the 1st law as well?  

RE: Question about 1st and 2nd law


IRstuff, what do you mean by "routinely broken" ?

RE: Question about 1st and 2nd law

Entropy is loosely defined as "disorder."  Therefore, anything that results in more order is ostensibly decreasing entropy.  

Thus, the spontaneous ordering of atoms into crystals and aggregation of atoms into organic molecules have been touted as being contrary to the second law.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Question about 1st and 2nd law

No . The 2nd law  defines which directiion a process is likely to proceed.  If you postualte a process for which the 1st law holds, but the energy is being tranferred in the wrong direection ( based on 2nd law ) then you have your hypothetical scenario.

For example, the radiator on your car is hotter than ambient air temp, and the first law says the energy lost form one  body ( radiator) equals the heat gained by the other  body ( ambient). The 2nd law says the heat goes from  the hot body (radiator) to the  cold body (ambient). But you can pretend the opposite direction of heat flow, from ambient to radiator, meet the 1st law, and violate the 2nd law.

RE: Question about 1st and 2nd law

Draw the dotted line around a system which is less than the universe and you can see imaginary violations of the 2nd law all the time.  But the entropy of the UNIVERSE increases for all irreversible processes, and is zero only for reversible processes.  That includes the creation of new molecules, crystalization etc.

RE: Question about 1st and 2nd law


The construction of a skyscraper from materials originally dispersed over Earth, the ordered symbols on a printed page, the growth of a living thing from a random mix of molecules, the fractionation of compounds by distillation, or by crystallization, are all examples in which entropy decreases.

However, all those examples do not involve "closed" systems. The entropy decrease associated with those processes is more than balanced by the entropy increase elsewhere in the universe as moltenmetal says.

We cannnot escape the second law of thermodynamics.
Therefore violating it is just a creature of the imagination.

One may as well pay a visit to the following link:

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

RE: Question about 1st and 2nd law

Hi there:

One can write as follows:

First Law
Q – W = ?U

Second Law
?S = Q/T

Overall, entropy is always >= 0 ...

Thanks,

Gordan



http://engware.i-dentity.com

RE: Question about 1st and 2nd law

Supersonicisentropic

Was there a reason you asked?

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

RE: Question about 1st and 2nd law

First Law Of thermodynamics: The Best You Can Do Is Break Even

Second Law Of Thermo: You Can't Break Even

If you could break the second law, there would be perpetual motion....when was the last time you saw perpetual motion?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources