# Is there/what is the unit of cooling?

1. Dec 27, 2015

### H2Odrinker

I want to do a little inquiry involving water, and I need to know what the 'cooling down speed' of water is (how much heat a certain volume or surface of water emits per second). Can anyone tell me if there is a unit and/or formula for this?

2. Dec 27, 2015

### theodoros.mihos

Formulas are approximations of models used to understanding physical phenomena.
There are three different ways for heat transfer.
1. by diffusion
2. by current into liquid or gasses.
On a water system you can use all of them or you can ignore some of these, depends by your case.

3. Dec 31, 2015

### Cosmos

Here the rate of cooling depends upon the temperature difference between the water surface and the surrounding temperature & the nature of the surface....

4. Dec 31, 2015

### Cosmos

also.....Cooling capacity is the measure of a cooling system's ability to remove heat. SI UNIT: Watts

5. Jan 1, 2016

### CWatters

What Theo said in post #2

Water doesn't have "one" rate of cooling. It depends entirely on the situation. For example water in a Vacuum flask will stay hot for longer than the same water in a fridge or in a lake with a wind blowing. If the water was placed somewhere hot it might not cool down at all, it might heat up. There are different equations applicable to different situations.

6. Jan 1, 2016

### Cosmos

Well.....this this easily satisfies the newton equation:

Here a negative rate of change implies body is getting hotter while a positive rate of cooling implies the body is getting cooler.
Thus as CWatters said that it depends on the situation that is the ambient temperature.

7. Jan 1, 2016

### alw34

As noted, too many variables to provide an answer.

Try googling " how fast does water cool at room temperature"
for insights on those variables....

You can guess a hot flame raises water temp faster than a cooler one.
In general, the greater the difference in temperatures, the faster the cooling.....and heating.