Here's why:

* Gravity is a force of attraction between any two objects with mass. The Earth has a large mass, so it exerts a strong gravitational pull on everything near it, including liquids.

* Liquids, like all matter, are made up of particles that have mass. Therefore, gravity pulls on these particles, causing the liquid to flow downwards.

* This downward pull is what we experience as "weight". So, a bottle of water feels heavy because gravity is pulling it towards the Earth.

Let me know if you have any other questions!