If you put hot water in a vacuum flask, it keeps it hot, if you put cold water in it keeps it cold, How does it know?
2006-11-07 05:37:01 · 11 answers · asked by Anonymous in Science & Mathematics ➔ Physics
small microchip on the bottom, go on, have a look......
2006-11-07 05:39:03 · answer #1 · answered by cereal killer 5 · 0⤊ 0⤋
A vacuum flask is a Thermos flask. It has two walls, with a vacuum in between. The chemistry version is also called a Dewar flask. The vacuum prevents heat loss due to conduction or convection, and sometimes the walls are silvered to minimise heat loss due to radiation.
2016-05-22 07:55:44 · answer #2 · answered by ? 4 · 0⤊ 0⤋
Hi. The best technique for keeping water, or any liquid, hot is to fill the flask with hot liquid to preheat the flask (or cold liquid to precool it) then add the liquid. The temperature will stays closer to the original this way. The heat doesn't 'know', it just flows from hot to cold no matter where 'cold' is. Insulation slows this down.
2006-11-07 05:46:03 · answer #3 · answered by Cirric 7 · 0⤊ 0⤋
The flask is designed to minimise the passage of heat. This works in either direction i.e. it reduces heat transfer in or out depending on whether it is warmest on the inside or the outside.
The mechanisms of heat transfer are conduction (the passage of heat through a solid), convection (through gas or fluids) and radiation (from one surface to another without requirement of surface contact or convecting fluid).
The vacuum flaks consists of a vessel for holding the fluid surrounded by another vessel (the outer casing). Contact between the inner and outer vessels is mininised to reduce conduction. The space between the vessels is subjected to a vacuum to prevent convection and the vessel walls facing each other are silvered to reduce emissivity and so radiation.
So the inner flask is pretty well insulated and this prevents heat transfer in either direction keeping hot things hot or cold things cold
2006-11-07 08:35:05 · answer #4 · answered by spoon_bender001 2 · 0⤊ 0⤋
Try keeping an ice cream and coffee in the same flask, you'll find the flask gets confused. They're not very clever.
2006-11-07 07:52:35 · answer #5 · answered by bo nidle 4 · 0⤊ 0⤋
because its vaccumed its a good insulator, keeping the heat in and out so depending what you put in it depends on the way it works. when the flask is vacuumed it removes all the air and air is a good conductor of heat, with the air being removed the heat can't get in or out.
2006-11-07 05:42:48 · answer #6 · answered by chocchip24 2 · 0⤊ 0⤋
It doesn't know. Heat does not travel across a vacuum easily, so if you put hot liquid in, the heat can't flow out, and if you put cold water in, heat can't travel in from outside to warm it up.
2006-11-07 05:40:35 · answer #7 · answered by SteveA8 6 · 1⤊ 0⤋
Inate intelligence! Think if a simple flask is that smart what can robots achieve.
2006-11-07 07:25:07 · answer #8 · answered by pete h 5 · 0⤊ 0⤋
it works as an insulator. it doesn't let heat in or out. so the heat can't get out when you put anything hot in, nor can heat get in to make it warmer. when you out anything cold in heat can't get out so it won;t get colder, but heat can't get in so it doesn't get warmer.
2006-11-07 05:48:34 · answer #9 · answered by Anonymous · 0⤊ 0⤋
its made to work like that.
2006-11-07 05:39:25 · answer #10 · answered by neha 3 · 0⤊ 0⤋