Bad Manners said:
Now, here's something you can help me with: A Thermos keeps hot things hot and cold things cold but how does it know?
It doesn't. It insulates. There's no such thing as hot or cold, just less heat or more heat. A thermos prevents heat transfer (aka insulates). A cold item warms because the heat in the outside air moves to the cold item to remove the temperature differential. A hot item cools because the heat it contains moves to the outside air to again remove the differential.
A Thermos is made of a material (materials actually) which prevent the conduction of heat. (because its airtight is also prevents convection or the travel of heat through air) Because of this, the temperature differential is maintained, so hot things stay hot, cold cold. Interesting related point, if you don't 'heat' or 'cool' a thermos by pouring water or something else into it before your food/drink the conduction of heat to the (usually) glass interior will alter the temp of your food/drink but once the lining is the same temperature the conduction will stop and all will stay happily insulated.
/End of thermodynamics lesson for today.
If people would drive better in this city I would be all over that thing....
