water

[koamu05]

Which is heaviest cold water or hot water? why should one be heavier than the other can anyone explain please?

[mibn2cweus]

The increase of molecular activity (bouncing more vigorously against each other) due to heating causes a decrease in density. However water has an unusual behavior below 4 degrees centigrade.

details here

[heathfield]

A hot-air balloon rises in cooler air because its air is less dense than that surrounding it. A hot-water-filled balloon will act similarly in cooler water for the same reason.

[AGENT X]

at a molecular level the heated water becomes less viscostic but increases in size, it returns to it's original form when cooled, both weigh the same but heated water takes up more space. this doesnt work if you are working with ice.

[shammydodger]

Yes, but this doesn't answer the question.

1 kg of water will still be 1kg of water whatever the temperature. The mass is a function of the amount of matter, not the temperature.

Similarly, the weight of the water is a function of the acceleration due to gravity (in layman's terms, gravity) which is the same anywhere on the Earth (give or take) and certainly doesn't alter with temperature.

As usual, this is a question that has been badly set. "Heaviness" seems to have been used as a substitute for "density." Tocompound the problem, my pub quiz's "answer" was that warm water is heavier!

[koamu05]

Exactly! this was a question in a pub quiz and it caused quite a stir. That is why I put the question as it was put to us to see what answers came up. Incidently the quiz answer was the same as your's.

[shammydodger]

Koamu

I've just spent an hour trying to explain this tonight in my local. Of course, everyone's eyes glazed over, thinking I was talking sh1te or not caring. But, as we know, the quizmaster is ALWAYS right!

[shammydodger]

Koamu

In which case, both our quizmasters were wrong. Unless the question was considering only water between 0 and about 4 degrees Celsius, in which case the warmer water would be "heavier."

Why is heavier used as a synonym for denser in this case? When we talk about one person being heavier than another, we don't mean density, so why here? It's just sloppy thinking and poor science.

Rant over.

[shammydodger]

The same question has just resurfaced in my local. For the jackpot question, no less. Yet again, the quizmaster had the wrong answer. If I wasn't such a nice person, I could have glassed him (and the jackpot was only �20)