RE: BANG! . . . What was that?!

[AustinBoston]

 It turns out to have been a soda bottle, flexing beyond it s design capabilities.
 
 On our big cross-country trip, I took advantage of a large change in altitude over two days to illustrate that there was a distinct difference in atmospheric pressure at different altitudes.  We were over 9,000 feet in Jacob Lake, AZ, and would be below sea level in Death Valley NP two days later.  So I took an empty water bottle, capped it tightly, and set it where we could check on it from time to time.  Then at Badwater in Death Valley, we took it out to photograph near the low altitude sign.  It was half crushed by the change in pressure.
 
 The kids asked and teased to tightly cap an empty bottle and see what happened going up to high altitude, but PJay and I wouldn t hear of it.  We tried to find some balloons that we would put over the mouth of a bottle, but were unable.
 
 Three or four weeks later, on our way up through Rocky Mountain NP, there was the big BANG!  It sounded like something plastic, but loud...like a rock landing on the roof of the van.  An investigation revealed a mostly-empty soda bottle that had " inflated" , and in the process apparently snapped outward fairly suddenly.  Normally, I wouldn t expect quite that much pressure, but I think there were a number of contributing factors.  
 
 First, the bottle had probably been cold when it was capped.  Now it was quite warm.  Pressure from thermal expansion.
 Second, the bottle had about an inch of soda in it.  It was probably fresh when capped, but had been jostled until there was no carbonation left.  More pressure.
 Third, I ll bet that with the warming, some of the water in the soda had evaporated inside the bottle.  More pressure.
 Finally, we had climbed about 8,000 feet in the two days since one of the kids forgot about the bottle.  Pressure differential.
 
 At about the 10,000 foot level, the bottle could no longer hold it s shape and announced that to us all.  We are thankful it didn t rupture, or someone would have had a Mountain Dew shower!
 
 Austin
 

[MtnCamper]

 AustinBoston
Austin, We experience this a lot. Just from going 5500 feet to 8500 or 9000 feet. The Potato Chips inflate, Marshmallows get bigger, and you should see the gas can on the back of my trailer. It s plastic and inflates rather nicely.[]

[AustinBoston]

 MtnCamper

ORIGINAL:  MtnCamper
 
 Austin, We experience this a lot. Just from going 5500 feet to 8500 or 9000 feet. The Potato Chips inflate, Marshmallows get bigger, and you should see the gas can on the back of my trailer. It s plastic and inflates rather nicely.[]
 

 We stopped at a snack shop at 8,000 feet and all the chip bags were inflated.  All but one, that is...it got the kid s curiosity, but I wouldn t let them buy it.
 
 Austin

[Foxyladies]

 AustinBoston
For someone who will be turning 50 next month.....I found this topic amazing. I was one who wasn t interested in anything to do with science while in school. What lessons to show your children......better than the school books. Thanks for posting!