hot
yes
When water is cooled, it shrinks. If the water is in a sealed bottle, it shrinks the bottle, too, collapsing it to some degree.
pour cold water over it
When we place a water bottle with cold water on top of a water bottle with hot water the particles in the hot water bottle rise, pushing the cool particles to the bottom. This is a type of heat transfer called convection. Basically, the hot particles in the hot water bottle rise to the cold water bottle at the top and the cool particles in the cold water bottle at the top sink to the hot water bottle at the bottom. This is one of the three heat transfers. Convection occurs in gases and liquid.
it moist inside the plastic
Yes it does. Cold water freeze slower than normal or hot water.
Their both warm unless the cat is cold.
You fill the hot water bottle up with hot water and you place it on the spot that aches. It works just like an ice pack, but it's hot instead of cold!
To calm a budgie or parakete when its hot is to have a spray bottle of cold water and spray your budgie or parakete!
The best way to safely microwave a hot water bottle is to heat the water in a separate microwave safe container in the microwave and then put the microwaved, hot water into the water bottle.
Water can be hot or cold if you want