Re: [Phys-l] Crackling of a fire

[Bernard Cleyet <bernardcleyet@redshift.com>]

We occasionally suffer from cold snaps (outside ~ 0 C; this is the  
coast of California, remember?).  Last time this happened I used  
recently cut wood which exploded.  I then placed wood soon to be used  
in front of the fire place to dry.  The explosions were noticeable  
less.  [Anecdotal and should be treated as such.]  I also noticed  
difference between pine and harder woods.  IIRC, tho a hard wood,  
eucalyptus, especially bad.

bc

p.s.  The cover over our wood storage was winded off, so the water  
soaking may have been a contributer.



On 2009, Jan 22, , at 11:52, Steve Highland wrote:

> I think it would be fun to dehydrate some firewood (what would be  
> the best
> way?) as much as possible and then build a fire with that to see if it
> crackles less.
>
> Experiments with fire are always fun...
>
> Steve in Duluth
>
>
>
> > A student has posed this question to me, and I'm not sure I have a  
> > good
> > answer, so I am seeking help...
> >
> > The Question:
> > Why, when you put a log on the fire does it 'pop, crack and crackle'?
> >
> > My proposed answer:
> > I think the answer lies in the sap content, even i dry wood.  As  
> > the wood
> > gets hotter, the sap trapped within the fibers heats and then boils
> > bursting forth, breaking the fibers giving the 'crack' sound.  Sap  
> > trapped
> > at the surface would expand and then burst giving the 'pop' sound.
> >
> > Refinements, clarifications, and debunking are welcome!
> > Thanks,
> > Peter Schoch
> >
> > _______________________________________________
> > Forum for Physics Educators
> > Phys-l@carnot.physics.buffalo.edu
> > https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
>
>
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