When you tilt a bottle containing water, the water that flows into the cup depends on the orientation of the bottle. If you tilt the bottle with the opening facing downward, the water that flows into the cup comes from the bottom of the bottle. On the other hand, if you tilt the bottle with the opening facing upward, the water that flows into the cup comes from the surface of the water in the bottle.
The reason for this is related to gravity and the behavior of fluids. Gravity pulls objects downward, including the water in the bottle. When you tilt the bottle with the opening facing downward, the force of gravity causes the water to flow out from the lowest point, which is the bottom of the bottle.
Conversely, when you tilt the bottle with the opening facing upward, gravity still acts on the water, but it cannot pull the water out from the bottom of the bottle because it's now higher than the surface level. Instead, the surface tension of the water and the air pressure above it play a role. When you tilt the bottle, the water surface curves upward, and the water flows out from the surface into the cup.
It's important to note that the flow of water depends on the angle and speed at which you tilt the bottle. The precise dynamics can vary due to factors such as the shape of the bottle, the amount of water inside, and the presence of air bubbles or obstructions.