Question

What happened when you placed your bottle system
in cold water?

Answer 1

Basically the temperature of the water will go dramatically down. Whenever water becomes hot it suddenly heats up in which creates the water particles within the bottle. It proceeds to move more enhancing better movement in motion which is involved in kinetic energy and yet soon makes the particles separated between the two.

Answer 2

The water level in the pipe went down.] ... [The hot water in the cup heated up the water particles inside the bottle. They began to move more. Greater motion (kinetic energy) pushed the particles farther apart, resulting in expansion.