how cold does water have to be for you to get hypothermia?
354289
i think it has more to do with how long youre exposed
1058355
its actually a general question. depending on the conditions and by what. even though blood is a bit thicker than water. the body is 70 percent water. water can freeze at 32 degree's and at 0 degree's can freeze solid in 45 minutes. the body itself will always freeze slower say if your in the artic naked with a glass of water. because the skin acts as a thermal barrier, it would take longer. put a cup of blood and a cup of water in the freezer and the blood will gel up at 0 degrees or less. the water in blood will freeze, but not the plasma. there is what is called freeze dried blood that can be used in research. if you put blood and water in hydrogen, they both would freeze solid as its 220 below zero.
1106588
Normally at 0ºC or 32ºF.  At that point water just begins to crystalize.\n\nThere are cases when water will not freeze, like \n- freezing point depression due to hydration,\n- freezing point depression due to osmotic effects (these are both equilibrium effects),\n- supercooling: the delay or absence of formation of an ice crystal in the absence of efficient ice nucleators and/or\n- the high viscosity\n\nFor every 0.5ºC (1ºF), water's viscosity will change by about 1.5%.\n\nWater viscosity is inversely related to temperature. The lower temperature, the higher viscosity.\n\nBut, water's dynamic viscosity at 0ºC is 3.732µ [ 10-5 (lb.s/ft2)] and the kinematic viscosity is 1.924v [10-5 (ft2/s)].
925921
like what do you mean,like why can you swim in cold weather? because the water is a higher temperature then outside...im learning this right now in science,but i dont listen alot...lol..sorry
278201
Considering body temp is 98 degrees normally, 70 degree water would be cold or cool depending your preference.\n\nLittle science experiment--If you want to test it out fill a basin with water that is 70 degrees (use a thermometer to check it) and stick your feet in it.  Then you'll know if you think 70 degrees is cold for the beach or not.
199763
What context are you describing (or is that what you are asking)?\n\nHot water will freeze slower than cold water.  In order to freeze the water temperature must be dropped to freezing temperature, and the farther away you are from freezing, the longer it will take to 'bleed' the temperature away by any known method.\n\nI am not aware of any condition where hot water will freeze faster than cold water, assuming the water in both situations is exactly the same (i.e., not water made of different material, or with another chemical in aqueous solution), so if someone can give this example, I would be very curious to see it.\n\nPerhaps there is a situation where you can heat a liquid to convert it into gas, and then from gas directly to solid (frost formation is an example of this).  I am not sure, but this might be one approach to try getting water to go to a solid state faster when the water temperature is initially higher.  The key is you are bypassing the liquid state.\n\nAddendum:\nActually now that I think about it, I have an aswer.  If you have supercooled water, i.e. water that is below freezing, it could stay in that metastable state indefintely.  So here is a case where hot water would cool faster.  The hot water will cool down to freezing and will freeze, while the supercooled water may never turn solid.\n\nAddendum:\nWow, this link that someone below posted is interesting:\nhttp://math.ucr.edu/home/baez/physics/General/hot_water.html\n\nI was going to say that it is impossible, since water at a higher temperature would have to pass through all lower temperatures, but this article pretty much explains it (in that, well, we just don't know).  It has been observed, but there is no explanation that can be agreed upon.\n\nTo be completely pedantic, I note that most of the explanations point to what I would consider to be "experimenter's errors" in the set up of the experiments (if more dissolved gas is in hotter water, than the two water mixtures are certainly not the same, so this is an invalid experiment... if there is a 'hot top', then the experimenter did not start with a homogenious mixture, and that has to be mentioned in the experiment... if the surrounding environment is not the same, then the ambient conditions are changing which not an assumption in a traditional experiment, but rather a source of error... if evaporation is allowed than some quantifiable mass of the water is not turning solid, so this again is invalid).  The only explantation that doesn't result from a poorly set up experiment is supercooling.
801436
Use specific heat capacities and latent heats of these materials along with your head to get water at 0C
620337
try drinking a cold glass of water.
830202
Depends on pressure/altitude.  At sea level its about 100C or 212F.
108830
i think water even in the upper 60s is safe. did it all of the time as a kid. feels cold but you get used to it and its not so cold as to make you sick.
237724
Infact, FLOWING water does freeze. but FLOWING WATER cannot freeze completely at 32 degrees providing it is attinaing warmth from somewhaere else. If you check the temp of a glass of ice water. It is 32 degrees but it is not completely frozen! 32 degrees is when ice begins to form &/or can sustain itself. The only reason your ice melts is because the water temp surrounding the ice is conducting the heat of the room which in turn tries to rise the water temp. While the ice is trying to hold the temp @ 32 degrees. Eventually the ice will melt; it releases cold in the form of water, to cool the water surrounding it. But because the warmth of the room is indefinate, the ice will eventually melt away as it is unable to hold the temp. Now if you put you ice water in a freezer that's set at 32 degrees. Your water will freeze. Because the water is no longer drawing the energy it needs to sustain its heat so the ice wins and freezes the water. \nSo how the heck does this pertain to rivers and moving water?\nMoving water is gaining warmth from the ground and the air. but becaue its moveing the temp of 32 degrees is not easily sustained so the ice melts and refreezes as it travels, because the weather changes and temps change ect. The only way to freeze moving water it to either:\n1. Have it be so cold that the water nearly immidiatly freezes (well below zero) or \n2. Have a sustained temp of below 32 for several hundreds of miles. \nNow if you put the water in a water rocker and put it in the fridge at 32 degrees it will freeze solid at some point because the temp is sustained and really how long it takes for it to freeze is the ultimate question. which depends entirely on the temp.\n-hope that helps
1010323
yes... 64 degees is very cold... you will need a wet suit to prevent hypothermia. A temperature between 78 and 81 is usually preferred. The bad part is, you part of the ocean rarely achieves these warmer temps.
745215
The answer is yes. And I bet you want more of an explanation, which gets a little tricky. It would seem evident that cold water would freeze faster than warm water. But there have been raging debates in scientific circles over whether that's true or false. The fact is a lot of different factors contribute to how fast water freezes, including its beginning temperature.\n    Physicists writing in the journal Scientific American have waded into the fray and have probably come the closest to a satisfactory answer. Quoting Paul G. Hewitt in the book Conceptual Physics, the Scientific American writers believe that hot water will freeze faster than lukewarm water, but not faster than cold water. (Except under certain circumstances.)\n    According to Scientific American, water at 90° C will freeze before water that is 60° C. Below 60° C, however, there is a switch and the cooler water will freeze faster. For example, 30° C water will freeze faster than 60° C water. It has to do with the water evaporation of the hot water immersed in a cold environment. The rate of cooling by evaporation is way higher for hot water than for the cooling of lukewarm water.\n    Now, for those certain circumstances. When you put a pan of cold water and a pan of hot water in a freezer (both pans have equal masses of water), the hot water experiences this rapid evaporation AND freezing from below, which cools water on the bottom of the pan. Because the surface water is already warm or hot, the water at the bottom just sits there instead of rising, getting colder and colder. The water at the top experiences evaporation. The combined effect could make the hot water freeze faster than the cold water.
825292
i guess I'm wrong   but I thought that water would  freeze at 0  degrees celsius.  also it would boil at 100 degrees C. Even in a vacuum.  my guess!  btw at absolute 0  kelvin,  does that only exist in a vacuum?  If we could reach  - 450 degrees F.  would our cpu's operate at an infinite speed.....got me on this one.  I'm not sure on how atmospheric pressure relates to these conditions.  But I know someone knows!
270930
Not very long. In most circumstance 5-7 minutes. However, in some cases, let's say, when someone falls into a half frozen pond or something, the cold is suppose to slow down their body system enough that there have been a few cases where people have been pulled out of FREEZING water 20 minutes later and they lived. Some may have had brain damage but they lived. I hope this helps!
1080300
u can't have water upto 40 below zero!!!\nthe lowest temp(in centigrade) u can reach is -12 c \nthis is achieved by a process called super cooling\nin this the temp of the surroundings is controlled, and care is taken that the surface of the water is not disturbed\nsimilarly u can super heat water upto 137 c
868477
water freezes at 32 degrees Fahrenheit, and 0 degrees Celsius\n\nthe colder the faster