I think this problem has problem

[wrrrr95]

Hi guys! I'm a high school student in korea. I was doing homework then, i found that i couldn't understand sth.

When i pull a rubber band, that will make rubber molecules equall but also make them hot.
The problem said 'the entalpy of rubber band when you didnt pull has higher entalpy than you pulled'

Buttttt i think that i worked to the band, so the heat was from work.
It can't define the higher entalpy because of release of heat.

Did i wrong?

 

[CWatters]

Stretch the band and allow it to return to it's original temperature. When you relax the band heat flows into the band from it's surroundings. Therefore it's entalpy increases.

 

[NascentOxygen]

Hi wrrr95, http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

When i pull a rubber band, that will make rubber molecules equall but also make them hot.

Actually, stretching makes them cold. You could concoct a crude refrigerator by stretching rubber bands.

 

[TSny]

wrrr95, you might enjoy this short video: Fun to Imagine