Newton's Third Law: For every action, there is an equal and opposite reaction.

How it applies to a rocket bottle:

1. Action: The rocket bottle expels pressurized air (or water, if it's a water rocket) out of its nozzle. This is the action force.

2. Reaction: As the air (or water) is pushed out, it exerts an equal and opposite force on the rocket bottle itself. This is the reaction force.

3. The Result: This reaction force pushes the rocket bottle upwards, causing it to launch.

Think of it like this:

* Imagine you're standing on a skateboard and you push off the ground. The force you apply to the ground (the action) causes the ground to push back on you (the reaction), propelling you forward.

* The rocket bottle does the same thing. It pushes the air (or water) out of its nozzle, and the air (or water) pushes back on the bottle, sending it upwards.

Important Note: The mass of the air or water being ejected is much smaller than the mass of the rocket bottle. However, the high velocity at which it's ejected generates a significant force. This is why a rocket bottle can launch even though it's relatively heavy.