Water bottles on a plane and the pressure | Hey Ray
PITTSBURGH (KDKA) - If you ever take a trip on a plane, a reusable water bottle is allowed, but certain kinds can turn into a hilarious water fountain that has the ability to soak you and some of your fellow passengers!
Well, hilarious to those who are not wet.
As a plane or jet climbs in altitude, the pressure drops. The pressure drops inside the aircraft, too. When the pressure drops inside the plane, closed containers act differently. When the pressure drops in the cabin of the plane, what air is in a container expands to fill the space left by the drop in pressure outside of it.
We have done experiments with the density equation before.
Notably, in one experiment where we dropped the pressure around marshmallows. This causes the air bubbles inside them to expand. This same process can cause snack bags to expand and it can impact certain types of water bottles.
You might be thinking, "Wouldn't all water bottles have a pressure increase inside?" The answer is "yes." Any closed container would have that expansion occur inside.
Normally, that pressure is quickly equalized when you open the water bottle up on the plane, causing a mess or anything noteworthy. Water bottles with straws are much different and can create a cool science experiment. Well, a cool experiment as long as you are not the one who gets wet.
So, why does the straw matter?
As the pressure in the plane's cabin decreases, the volume of air inside the bottle expands, as we mentioned.
This creates a force that pushes down on the water, which in turn pushes pressurized water up the straw. When you flip that straw out, the water is forced up the straw, as the pressure in the bottle and the plane's cabin try to equalize.
If you have a bottle with a straw, you can open the lid as your plane climbs high into the sky. That should keep the pressures equal. A descending plane can cause some cool things to happen, too.
If you finish a disposable water bottle when the aircraft is at its highest altitude, and put the cap back on tightly, when the plane lands, the higher pressure inside the cabin will crush the bottle.
The volume inside the bottle decreases, causing it to crush...Especially if that disposable water bottle is made of flimsy plastic.
Now you have a science experiment for your next flight, and can stay dry because you know how it works!
