[DVBC] Physics question

[Dave Hartrum]

That's it. Put your cell phone in the water bottle and it won't freeze.


Dave Hartrum
dhartrum at mac.com



On Jan 22, 2007, at 12:05 PM, Doug Bower wrote:

> Dave,
>
> Javier is correct.  If you look at the heat transfer formula, heat
> transfer is a function of the Delta temperature between one medium and
> the other times the velocity of the material times the surface area of
> the transfer area and last but not least the heat transfer of the
> material(known as K, how well a plastic bottle transfers heat).  The
> surface area of Bob's bottle is fixed, the delta temp is somewhat  
> fixed
> but the velocity between the water and air is a variable.  Basically
> anything to increase velocity of the air or water will increase heat
> transfer.  But this will only speed up the freezing and not affect the
> temperature at which Bob's bottle froze.
>
> Dave, Stick to cell phones. :)