How much would a glass of water lower your body temp.

Question

i tryed figuring it out but didnt get a good answer. got about 1/3 of a degree if the water was 50 degrees and your body was 100( to round it) what is the right answer i always wandered.

Answer 1

I'd consider the human body to be pretty much the same (thermally) as water, so this should be pretty much a problem in proportion.  

You need to consider the relative mass of the water and of the body, and their temperatures, and without those numbers I can't evaluate your 1/3 degree result.

Answer 2

Suppose you weigh 70 kg (about 150 pounds).

Water is about 1 kg per liter. So if you drink a big glass, 1/2 liter, that's about 0.5 kg.

As someone else said, you're body is mostly water, so if you assume the specific heat of your body is the same as of water, about 4.186 J/gram/degC

Assuming water is 50F, that is 10C.

Your body is 100F, or say 40C.

If you assume a simply model where you add water, and then the water heats up and your body cools down to the same final temperature.:

Heat gained by water and body respectively is given by:

Qwater = c*mwater*(Tf - 10)

Qbody = c*mbody*(Tf - 40)

where mwater is mass of water, mbody mass of body, and c is specific heat.  We require that the heat gained by the water is equal to the heat LOST by the body:

Qwater = - Qbody

so mwater (Tf - 10) = mbody(40-Tf)

or solving for Tf

Tf = (mbody*40 + mwater*10) / (mbody + mwater)

using our assumptions mbody = 70kg, mwater = 0.5 kg

you get about 0.2 Celsius change, or about 1/3 degree as you calculated!

I think in reality, the answer is more complicated than that, since your body is not just at thermal equilibrium, it has its own power plant that can generate heat or sweat to maintain about a constant temperature.

Also, we assumed specific heat of the body is the same as water -- but if you look online

http://www.engineeringtoolbox.com/human-...

you will see that it is somewhat lower (3400 J/kg/C, vs 4186 J/kg/C) -- the result of which would tend to make you seem to weigh less in the above calculation (50 kg vs 70 kg) which changes the answer somewhat.

Answer 3

specific heat of water is 4.186 kJ/kgC

density of water at 20C = 0.998 g/cm³ = 998 kg/m³

take one cup of water or 0.00024 m³ or

0.00024 m³ x 998 kg/m³ = 0.24 kg

Average body mass is 90 kg, consider it all water.

don't even need specific heat, it's all proportions.

0.24 kg / 90 kg = 0.0026.

so a cup of water at 20C is warmed up to 37C, with a change in 17C

That is reflected in a change in the body of 17*0.0026 or 0.04 degrees.

edit, got confused between C and F

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