[Shalini]

Shalini asked the Naked Scientists:
   
Paper is combustible but we can boil water in paper cup, why?

What do you think?

[peppercorn]

Lower the air pressure?

[Joe L. Ogan]

If heated in the microwave it only gets up to 212 degrees which is not hot enough to cause the paper to ignite.  Thanks for comments.  Joe L. Ogan

[maffsolo]

I agree with Joe L. Ogan

Water has many uses, one we can associate with being the better of the least expensive heat sinks.
 Water cooled engines to water cooling your feet, or a blacksmith uses it to cool his work somewhat.

Instead of a paper cup let's use something more flammable, a Styrofoam cup.
It ignites and burns faster than a paper cup.

!!!! Caution not to burn your hand by the flame !!!!

If you put water in the Styrofoam cup, you can sit the cup over an open flame and it will never burn through as long as there is water in the cup opposite the flame.

Same reason that plumbers, ideally, drain the water out of the copper plumbing before sweating a coupling on the copper pipe. If the water is permitted it will create vapor that will heat sink up to 212 degrees F.

To melt solder to sweat copper pipes, you need at least something in the neighborhood of 6 or 7 hundred degrees F.

There is advertisement associated with the infomercial. I extend my apologies
http://www.metacafe.com/watch/835628/macgyver_style_diy_tip/
 
Darn I swore it was chocolate milk ma...

[Geezer]

Peppercorn is also correct. You can make water boil at room temperature by reducing the air pressure.

[Joe L. Ogan]

I have found that you can make me boil if you reduce the room air pressure enough!  Please excuse my pun.  Thanks for comments.  Joe L. Ogan

[maffsolo]

Peppercorn is also correct. You can make water boil at room temperature by reducing the air pressure.

Yep  that is a fact.

Shalini asked the Naked Scientists:
   
Paper is combustible but we can boil water in paper cup, why?

What threw me was the mention of combustion.
That is what dictated my statement.

[rosy]

I believe it's possible to heat water to boiling point over a fire in a leather "bucket"... provided it's wet, the heat will always be transferred to the water and thus the leather never gets hot enough to char.
I guess this is actually equivalent to the more familiar effect of a candle/lamp wick which doesn't burn so long as it's soaked with fuel.

[Geezer]

I believe it's possible to heat water to boiling point over a fire in a leather "bucket"... provided it's wet, the heat will always be transferred to the water and thus the leather never gets hot enough to char.
I guess this is actually equivalent to the more familiar effect of a candle/lamp wick which doesn't burn so long as it's soaked with fuel.

I seem to remember that some peoples boil water in a woven basket by chucking a very hot rock in it.

That's all I have time for right now. I need to get back to my basket weaving.

[luvinia1973]

Because of the high ignition paper, the water after boiling has not yet reached the ignition point of paper.So it can be.

[SeanB]

I have boiled water in a paper cup over an open fire. This works as the water does not allow the paper to reach above 100C, at least that part in contact does not burn, though the rest of the cup may burn a little. This is because the paper is a reasonably good conductor of heat, and transfers the heat to the water without getting too hot itself. Trying this with a polystyrene cup will result in the cup melting, as the insulating property of the cup allows the outside to get hotter than the water inside.