volume of air

[helbee]

Wanting to fill up an airbed to a certain pressure with a pump, would it be quicker with +19 degrees or -4 degrees?

 

Regards Helbee

[Sisyphus]

This wouldn't happen to be a homework question, would it?

[MattC]

Well, assuming you are talking about + or - degrees temperature of the airbed, and assuming this is a homework question (it does sound like one), here's your hint:

 

PV=NRT (for an ideal gas - no gasses are ideal, but they all pretty much obey this rule, with only slight amounts of error)

 

Pressure X Volume = NumberMolecules X R (gas constant - 8.31 in this case) X temperature

 

That is the equation. The number of molecules is constant. The value R is constant. The volume varies, but by the time you get it almost fully inflated, it's pretty much statis - at least, it doesn't change much, and isn't important.

If you increase T, what does P have to do, for the equation to still work? If you decrease it, what must T do, then?

That's your hint! Good luck!

[YT2095]

it`s actualy a trick question!

[Pleiades]

That’s what I was thinking; the room temperature has no effect on the time it takes to fill the airbed. Now, if you filled it up part way, with cold air outside in the winter, then brought it inside and warmed it up, the air would expand filling the bed the rest of the way. Hope I didn’t take all the fun out of the trick question.

[insane_alien]

better yet, use liquid air! only need a few spoonfuls