Why does hot water go up and cold water

go down?

Step-by-step explanation:

Any object or substance that is less dense than a fluid will float in that fluid, so hot water rises (floats) in colder water ... Any object or substance that is more dense than a fluid will sink in that fluid, so cold water sinks in warmer water. Hot air rises and cold air descends for exactly the same reason.

Any object or substance that is less dense than a fluid will float in that fluid, so hot water rises (floats) in colder water ... Any object or substance that is more dense than a fluid will sink in that fluid, so cold water sinks in warmer water. Hot air rises and cold air descends for exactly the same reason.