Dying of hypothermia?

OK, so let's say someone jumps in the lake or ocean when it's December. Really really cold.

The water temperature is about 20-30 degrees (for example).

Would they automatically die? How long would it take?

If they got OUT of the water within 2 minutes, would they still live?

This isn't homework , just my twisted mind.

You can last longer than 2-3 minutes. It depends on the person, but I've been on ice rescues where people where in the water 20 minutes and just fine. The water definately sucks heat out quickly, but if not rescued....yes they will die. Hypothermia is a bitc...h!

idk. but it's funny the weird things people wonder. i do stuff like that too. lolz.

They'd be dead if they were in the water for two minutes. They'd have to get out within 5 to 10 seconds if they hope to survive. Even then, if they do get out, they'd require immediate attention, and if not they would die by themselves in the cold.

Stages in humans
Normal body temperature in humans is 37掳C (98.6掳F). Hypothermia can be divided in three stages of severity.

In stage 1, body temperature drops by 1-2掳C below normal temperature (1.8-3.6掳F). Mild to strong shivering occurs. The victim is unable to perform complex tasks with the hands; the hands become numb. Blood vessels in the outer extremities constrict, lessening heat loss to the outside air. Breathing becomes quick and shallow. Goose bumps form, raising body hair on end in an attempt to create an insulating layer of air around the body (limited use in humans due to lack of sufficient hair, but useful in other species). Often, a person will experience a warm sensation, as if they have recovered, but they are in fact heading into Stage 2. Another test to see if the person is entering stage 2 is if they are unable to touch their thumb with their little finger; this is the first stage of muscles not working.

In stage 2, body temperature drops by 2-4掳C (3.6-7.2掳F). Shivering becomes more violent. Muscle mis-coordination becomes apparent. Movements are slow and labored, accompanied by a stumbling pace and mild confusion, although the victim may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm. The victim becomes pale. Lips, ears, fingers and toes may become blue.

In stage 3, body temperature drops below approximately 32掳C (90掳F). Shivering usually stops. Difficulty speaking, sluggish thinking, and amnesia start to appear; inability to use hands and stumbling are also usually present. Cellular metabolic processes shut down. Below 30掳C (86掳F) the exposed skin becomes blue and puffy, muscle coordination very poor, walking nearly impossible, and the victim exhibits incoherent/irrational behavior including terminal burrowing or even a stupor. Pulse and respiration rates decrease significantly but fast heart rates (ventricular tachycardia, atrial fibrillation) can occur. Major organs fail. Clinical death occurs. Because of decreased cellular activity in stage 3 hypothermia, the body will actually take longer to undergo brain death.

ummm......i'd like to see someone jump into a lake that was 20 degrees ferenheit......last i checked, it was physically impossible to jump into an iceblock!