Why might hot water be a good choice to use for filling a bottle to keep your feet warm at night?

Question

why is it not a good choice to put it in an insulated thermos bottle if you wanted to feel the warmth?

Answer 1

Because is cheap, easy to heat and easy to transport from the pan to the bottle, and the releasing temperature is quite close to the human body.

Other than that, to keep your feet warm, wear a hat. Your head dissipate a great amount of heat, keeping your head warm, all your body will follow.

:)

Answer 2

Water is good because it has a high specific heat capacity, it takes a lot of energy to heat it and it releases a lot of heat while it is cooling. It wouldn't be a good idea to put it in an insulated bottle because the insulation will absorb all of the heat.