How long does it take water to cool from 70 degrees to room temperature 21.5 degrees?

Question

How long does it take water to cool from 70 degrees to room temperature 21.5 degrees?

Answer 1

How much water?  Surface area? Shape?  Air movement? Insulation? Ambient temperature?

Answer 2

spill one ounce of that water on the floor and it will cool relatively quickly. leave a gallon of it in a insulated cup and it is going to take considerably longer.  you have to many unknowns in your question.

Answer 3

need to know the area per unit volume... Also the container the water is in its shape is it opn... The specific heat capacity of the material of the container... It's thickness...

Not that simple i'm afraid.

q =mCp.dT will give you the energy lost but the rate is a combination of conduction and convection mechanisms... The rate of change of heat transfer will diminsh also as the water cools. So you got your work cut out if this science homework. I think it took about 3 hours of lectures to explain the theory behind something like this when I studied Chemical Engineering...

Perry's Chemical Engineers Handbook has everything you will need to work something like this out. It's more of a tree trunk than a hand book though.

Answer 4

depends on the volume of water because water has a relatively high SHC

usually 4 minutes tops