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Why did our helium balloon get new life?

Posted: Mon May 20, 2013 7:45 pm UTC
by albionmoonlight
My son had his birthday a few weeks ago. We had a Mylar helium Winnie the Pooh balloon attached to the mailbox. A couple of days after the party, it was hanging there--just at the point where it would fall to the ground, but very very slowly. So we took it down and started hitting it around (note: when you have a five-year-old boy and a two-year-old boy, you will use the phrase "so we . . . started hitting it around" a lot). Soon, it started to act a bit lighter, but it still was coming down, so we kept hitting it.

Then, it started to rise and kept going and going and going. And it flew away.

I am assuming that by hitting the balloon around, we gave it energy, which expanded the gas, which was enough to make it lighter than the air. However, it occurred to me that I might be wrong about that. So, I am writing here to confirm or contradict or expand/flesh out my assumption.

Thanks.

Re: Why did our helium balloon get new life?

Posted: Mon May 20, 2013 8:34 pm UTC
by scarecrovv
That's pretty cool! I wish you had a video of it. I think you're probably right. Every time you hit it, you increased the temperature of the gas, which increased the volume, which reduced the density, which increased the buoyancy.

Re: Why did our helium balloon get new life?

Posted: Tue May 21, 2013 1:54 pm UTC
by p1t1o
If it was right on the cusp of having the same density as air, a local pressure change might have contributed to buoying it up.

Did the weather change at all near the time of the incident?

Re: Why did our helium balloon get new life?

Posted: Fri May 24, 2013 6:24 pm UTC
by albionmoonlight
p1t1o wrote:If it was right on the cusp of having the same density as air, a local pressure change might have contributed to buoying it up.

Did the weather change at all near the time of the incident?


No. It was kind of cool and humid. The whole thing took about 10 minutes at the most, and no noticeable weather changes during that time.

Re: Why did our helium balloon get new life?

Posted: Sat May 25, 2013 6:59 am UTC
by tomandlu
Slightly OT, but what I love doing with helium balloons is weighting them so they just hover indoors and then leaving them. They turn up - occasionally rather alarmingly - all over the house, drifting around like ghosts, unfazed by stairs or doorways.

Re: Why did our helium balloon get new life?

Posted: Sun May 26, 2013 3:49 pm UTC
by The Geoff
If it was humid, is it possible water was condensing on the balloon and weighing it down, and you then batted the water off letting it rise? Just a thought.

I prefer the hitting->energy->volume idea myself, much neater and more sciency :)

Re: Why did our helium balloon get new life?

Posted: Sun May 26, 2013 4:15 pm UTC
by eternauta3k
You might have beaten off some dust, too.