Hold the bottle and pull down on the knot of the balloon at the bottom. Describe what happens to the balloon inside the bottle.

When you hold the bottle and pull down on the knot of the balloon at the bottom, you are creating a scenario that involves pressure changes in the air inside the bottle and the balloon.

1. Initial Condition: The balloon is inflated with air, and it occupies a certain volume inside the bottle. The air inside the bottle is already at a certain pressure.

2. Action Taken: By pulling down on the knot of the balloon, you are effectively elongating the balloon and reducing its volume.

3. Pressure Dynamics: As the volume of the balloon decreases, the pressure of the air inside the balloon increases due to Boyle’s Law, which states that pressure and volume are inversely related for a given mass of confined gas when temperature is constant.

4. Behavior of the Balloon: As you continue to pull down the knot, the balloon will initially resist due to the increased internal pressure. However, if the balloon is stretched enough and the external air pressure allows it, you may observe that the balloon starts to collapse inward or prevent further inflation, as the external pressure may become greater than the internal pressure.

5. Resulting Effect: Ultimately, depending on how much you pull down, you may see the balloon either deflate partially or remain in a stretched state with the air pressure balanced, but it will not inflate further because it is constrained within the bottle.

This action illustrates principles of gas laws and the relationship between pressure, volume, and the behavior of gases when restricted in space.