Bloggers Wanted
We're looking for people to help with the main blog. If you are consistent, knowledgeable and you're into it, please drop me a note.
|
|
|
|
|
MYLITRON
 Fresh Boarder
Posts: 19 
|
|
Have a basic scientific question about the origin of the buoyant force that lifts a hot air balloon.
Consider these two explanations:
(1) The buoyant force is caused by the fact that air pressure decreases with altitude. Therefore, the force pushing 'up' on the bottom of the balloon is greater than the force pushing 'down' at the top.
(2) The buoyant force results from the fact that gravity will favor a fluid falling to take the place of an object less dense than the fluid (since more mass goes down than up).
|
|
The administrator has disabled public write access. |
imported_Adrian
 Fresh Boarder
Posts: 18
|
|
A balloon rises because the air inside is less dense (because it is warmer) than the air outside.
Your first explanation is true, but the pressure differential between the bottom of the balloon and the top of the balloon is so small that it might as well not exist.
If you have ever flown under an inversion, where the air aloft is warmer than the air at the surface, you'ld know that the balloon stops rising when it reaches that warmer air, until you add enough heat.
|
|
The administrator has disabled public write access. |
|
|
|
