“For every action there is an equal
and opposite reaction.”
You chose wisely!!
Newton’s Third Law of Action-Reaction is the
essence of jet and rocket propulsion. Let’s look at a diagram
of the combustion chamber of a rocket (essentially your bottle).
If it were closed, the pressurized air would push
out on all sides equally, like a balloon.
However, open the nozzle and the escaping air leaves
an unbalanced force on the opposite side of the bottle.
The “action” is the
movement of air out of the nozzle. The “reaction”
is the forward motion of the bottle.
Part of what determines the bottle’s velocity
is the MOMENTUM (momentum = mass x velocity) of
the escaping particles. There is another law, called the Conservation
of Momentum Law, that requires the momentum of the bottle
(bottle mass x bottle velocity) to be equal but opposite to the
momentum of the escaping air (air mass x air velocity).
