The Naked Scientists

The Naked Scientists Forum

Author Topic: Why do bubbles float?  (Read 11223 times)

Gracie

  • Guest
Why do bubbles float?
« on: 25/10/2008 11:10:59 »
Gracie  asked the Naked Scientists:

Dear Dr.Chris and fellow Naked Scientists,

I was in my backyard blowing bubbles yesterday and wanted to know why bubbles act like they do. What makes them stick to the bubble wand and then come off when you blow, and why are they spheres?

I know that my breath is not lighter than air, because it IS air, so what makes them float? If you could provide somewhat of an answer to my queries, I would be forever grateful.

Grace
St. Louis, USA

PS: I love your show and listen to the podcasts all the time. Thanks and keep up the great work!

What do you think?


 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
Why do bubbles float?
« Reply #1 on: 25/10/2008 14:22:31 »
They probably stick to the wand due to a mixture of surface tension and the detergent in the water holding them to the wand

They are probably spherical because the membrane is of equal thickness and strength over the majority of its surface and because the air inside and outside is pushing equally in all directions onto the membrane.

Bubbles are not lighter than air but are mainly composed of air with an extremely thin wall of water and detergent which makes then very light and able to be blow about by wind and thermal currents.

Gracie

If Ive got any of it wrong or not explained it well enough you will receive other replies. 
 

Offline RD

  • Neilep Level Member
  • ******
  • Posts: 8123
  • Thanked: 53 times
    • View Profile
Why do bubbles float?
« Reply #2 on: 25/10/2008 16:50:04 »
Quote from: Gracie  link=topic=17863.msg201677#msg201677 date=1224929459
Gracie  asked the Naked Scientists:

I know that my breath is not lighter than air, because it IS air, so what makes them float
?

Your exhaled breath is warmer and consequently less dense (lighter) than the air in the atmosphere,
 (this is why a "hot air" balloon rises).
« Last Edit: 25/10/2008 16:51:36 by RD »
 

Offline Don_1

  • Neilep Level Member
  • ******
  • Posts: 6890
  • Thanked: 7 times
  • A stupid comment for every occasion.
    • View Profile
    • Knight Light Haulage
Why do bubbles float?
« Reply #3 on: 25/10/2008 16:54:56 »
You beat me to it RD. Your breath is sufficiently warmer than the air around you to make it lighter.
 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8645
  • Thanked: 42 times
    • View Profile
Why do bubbles float?
« Reply #4 on: 25/10/2008 21:06:05 »
Surely that's not going to be true for long? Once they cool the excess CO2 will make them denser than ordinary air. Anyway, in my experience bubles blown indoors (where there's no wind to keep them up) sink.
 

Offline ukmicky

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 3011
    • View Profile
    • http://www.space-talk.com/
Why do bubbles float?
« Reply #5 on: 25/10/2008 23:11:58 »
Quote from: Gracie  link=topic=17863.msg201677#msg201677 date=1224929459
Gracie  asked the Naked Scientists:

I know that my breath is not lighter than air, because it IS air, so what makes them float
?

Your exhaled breath is warmer and consequently less dense (lighter) than the air in the atmosphere,
 (this is why a "hot air" balloon rises).
  Surely it would depend on the environment you were in and what you were doing at the time you breathed. Maybe we should go and test that one out in the middle of the Sahara desert.
« Last Edit: 25/10/2008 23:16:29 by ukmicky »
 

Offline JnA

  • Neilep Level Member
  • ******
  • Posts: 1093
  • Stunt Scientist
    • View Profile
Why do bubbles float?
« Reply #6 on: 25/10/2008 23:30:22 »
I was thinking (obviously incorrectly) that breezes lift bubbles.. when we use bubbles inside our house they fall to the ground rather quickly.. but outside floaty floaty...
 

lyner

  • Guest
Why do bubbles float?
« Reply #7 on: 27/10/2008 17:10:38 »
The breeze does the same thing for feathers and dandelion seeds. With no wind they would float to Earth.
 

The Naked Scientists Forum

Why do bubbles float?
« Reply #7 on: 27/10/2008 17:10:38 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums
 
Login
Login with username, password and session length