MadSci Network: Chemistry |
Dear Catherine,
You need to first look at quite a few things:
- What is the density of air that is being filled in?
- How are you considering the sky (atmosphere)?
To understand an answer to this question, it is sufficient if you answer
the questions
above.
Density is a property of matter, that is the mass (or weight) of an object
in an unit
volume (unit volume=> 1 m^3 or 1 ft^3, etc.)
So if the gas that you filled it in with is lighter than air (like Helium,
Hydrogen,
etc.), then the tendency of that air is to move upwards. ( To understand
this you'll
need to get to the last part of the explanation.) If the weight of the
balloon is
nulled out by the effect of density, then the balloon will start to rise.
If the weighing is done on earth, then the object will tend to have a lower
mass and
weight. But this is just apparent weight. In reality all substances have
mass, and when
you add something to something else, you'll definitely end up with more.
(Again, to
understand this, please read the next paragraph, and get back and read this
paragraph
once again.)
You need to understand how the atmosphere functions. To understand it,
think of the
atmosphere as a big pool. If you get to the pool, and put something like
styrofoam, it
is going to float back up, the reason is that styrofoam is lighter than the
same amount
of water (density is lesser), but not massless. If you weigh it on land, it
does weigh
something, even though it is quite light, right. Now toss a penny into the
pool, it is
going to get to the bottom of the pool. The reason is that the penny is
heavier than
the same amount of water (density is greater.) In the same way all things
stay down on
the surface of the earth, because it is heavier than an equal amount of
air. Air and
Water are both fluids, and they behave in the same manner, This is one of
the
principles in fluids, that a lighter object than itself will tend to go up
untill its
density is equal to the density around it.
Thanks and Regard,
Abhilash J Markkassery,
Student, University of Texas at Arlington.
Try the links in the MadSci Library for more information on Chemistry.