Answer 1:
Well it is all about pressure. If you have a
VERY VERY STRONG container and at the Earth's
surface, fill it will soda and a little air and
then seal it, the pressure of the fluid in the can
will be about 1 bar pressure. Now if you put
that can in a rocket and send it to say earth
orbit, take the can out of the space ship and
think about the situation before opening, this is
the case: We have a fluid at 1 bar pressure
in a strong container (i.e. a container that can
support the pressure difference, what is the
pressure difference? Well it is zero pressure in
space and 1 bar pressure inside the can PUSHING
OUTWARDS IN ALL DIRECTIONS BUT NOT STRONG ENOUGH
TO BREAK THE CAN. Now what is "1 bar
pressure"? Well in the SI system of units 1 bar
pressure equals 100,000 Newton/square meter, that
says that there is a FORCE of 100,000 Newton per
meter squared. Now the surface area of a can
of soda is 2*pi*R*h where pi=3.14, R is the radius
of the can (about 0.03 meters and H is the length
of the can, about 0.1 m. To this we need to
add the area of the top and bottom which is
2*pi*R*r...so, roughly let us say that the area of
the can is 0.03 m^{2}. Then the
FORCE acting on the walls of the can OUTWARD is
(100000)*(.03) =3000 Newton. Just for a
comparison, the force i exert on the earth when I
stand on it is about 800 N!! So you can see
although it sounds like not much there is a large
force (pressure is simply the force per unit area)
that the fluid in the can is exerting. So
when you pop the can, there is going to be a large
unbalanced force and the fluid is going to expand,
the CO_{2} that is dissolved in the soda
will come out of solution and expand along with
the liquid itself... there will be a small
explosion and you will end up with a
mess!!! This discussion neglects temperature
and other factors... but the essence is that the
pressure will try to equalize to zero, the ambient
space background and THAT means the fluid will
EXPAND.
