Friday, August 31, 2012

Finising a Bottle of Canned Air

Have you ever noticed that canned air starts to have a weaker force behind the blowing when you get near the end of a bottle?  One reason is that you are running out of propellant.  Another reason is that the can gets cold.  According to the ideal gas law (PV=nRT if you've forgotten), when the temperature (T) falls, so will the pressure (P) since volume is held constant by the size of the interior of the can.  This means that when you think you're near empty, you can wait until the can heats back up to room temperature and get some more air out of the can.  There are diminishing returns to doing this.
Post a Comment