What freezes faster, a cup of warm water, or a cup of cool water and why?

Question

What freezes faster, a cup of warm water, or a cup of cool water and why?

Answer 1

It depends on their initial temperatures and surroundings.

A cup of warm water (70° F) in a freezer with a temperature of -40° F  will freeze faster than a cup of cool water (69° F) in a freezer  with a temp of +31° F due to the heat differential.

MY definition of cool is less than 70° F.

A cup of cool water in a refrigerator with a temperature of 38° F will not freeze at all!

How do you define warm and cool...

In science you need to DEFINE YOUR TERMS!

EDIT:

re: José's post -- In science you never assume anything!

If they are in the same environment, the cup of warm water has more heat in it. Heat transfer takes time.

.

Answer 2

Assuming identical conditions, then almost always, the cool water freezes faster, because less heat needs to be dissipated. However, under very carefully orchestrated conditions, you could get the warmer water to freeze faster by using very wide, open containers, thus allowing the pooled water to have an enormous surface area to volume ratio, which would allow the warmer water to shed mass and heat through evaporation at a much higher rate than the cool water, arriving at freezing temperature at a smaller mass than the liquid cool water remaining at that point, so that the identical rates of freezing result in the initially warmer (but now less massive) cup freezing first.

Answer 3

well more details are needed but a general answer is this:

according to newtons law of cooling the rate at an object cools is proportional to their difference in temperature.  meaning the greater the difference between the cups temp and the freezers temp the quicker it will cool initially.

but but there is no momentum in cooling.  so as the cup cools the rate of cooling declines and sense the warmer cup eventually gets to the same temp as the cooler cup there i no way the warmer cup freezes first.  exception if the one cup is boiling and the other is just a degree or 2 different then yes the boiling water will freeze first.

Answer 4

the time it takes to freeze surely would be the cool water, because it has less heat to give to the surroundings, and will hit freezing point quicker

but rate wise then maybe warm water, never actually thought of that one

Answer 5

The cool water will freeze faster because less heat energy must be transferred out of the water.

Answer 6

The warm water will freeze faster, since more heat is present in the warm water the heat will dissipate faster, this accelerated process will continue.

Answer 7

Cold water, as it has less heat to give off before freezing.  The warm water freezing is an old wives tale.  What happens with warm water is that some of it evaporates when put in the freezer, so less water is actually left to freeze.