how does a thermos flask keep hot things hot and cold things cold?

Answer 1

insulation traps the heat and cold

Answer 2

The thermos is a glass or metal container that seals in the liquid. It simply insulates the liquid from the outside for a while. Even the best thermos flasks only work for so long. A hot thermos of coffee will last from 6 AM through supper at about 5. After that, it will be pretty cool. Same with a cold thermos of milk. After sitting a few hours, it will assume room temperature.

Answer 3

Hi how is you day? Now the Flask is a mirrored glass with in a vacuum glass inside of a shell There are 3 parts plus the cap or lid. The shell will stop the otter atmosphere from the outer glass keeping the inner glass at a stable temperature of hot or cold. Preventing thermo energy from traveling pass a vacuum.

Answer 4

This is due to the vacuum between layers in the thermos. Heat cannot transfer through a vacuum. This and heavy insulation keep the heat trapped within a thermos.

Answer 5

A thermos in reality is a container within a container- it acts roughly like a calorimeter. The inner container (what you see when you peer in) is separated from the outer container (what you hold) by a volume of air. This air is what acts as the insulant. it keeps the heat or cold from escaping to the outer container (air is a poor conductor of heat or cold)
there you go. that's how it works.

Answer 6

The thermos bottle has a smaller glass bottle sealed inside with a vacuum-tight seal. The vacuum acts as an excellent insulator so what is hot,stays hot, cold stays cold. I hope this helps.

Answer 7

A practical vacuum flask is a bottle made of glass, metal, or plastic with hollow walls; the narrow region between the inner and outer wall is evacuated of air. It can also be considered to be two thin-walled bottles nested one inside the other, and sealed together at their necks.

Using vacuum as an insulator avoids heat transfer by conduction or convection. Radiative heat loss can be minimized by applying a reflective coating to surfaces: Dewar used silver.

The contents of the flask reach thermal equilibrium with the inner wall; the wall is thin, with low thermal capacity, so does not exchange much heat with the contents, affecting their temperature little. At the temperatures for which vacuum flasks are used (usually below the boiling point of water), and with the use of reflective coatings, there is little infrared (radiative) transfer.

The flask must, in practice, have an opening for contents to be added and removed. A vacuum cannot be maintained at the opening; therefore, a stopper made of insulating material must be used, originally cork, later plastics. Inevitably, most heat loss takes place through the stopper.

Answer 8

They work by insulating. The Thermos is an insulator, and has a tight and small top (to reduce heat loss). If you want to keep something extra cold, rinse it out just before use with extra cold tap water or if you are trying to keep it hot, put some boiling water in it to keep it extra hot for a longer period of time.

Answer 9

On the basis that a liquid (well, anything) has a tendancy towards becoming the same temperature as the environment that it is in, the insulation in the thermos minimises the conduction of heat, and protects the liquid from the external influences, allowing it to remain at a more constant temperature. I'm sure a physicist could give you a more accurate answer!

Answer 10

It is mirrored inside which reflects heat inwards, and it has a vacuum between the inner and outer parts of the flask, so that heat cannot travel from the outside or from the inside (depending on whether it's hot or cold) by convection (by currents in the gas or liquid) or conduction (by passing through a solid), but only by radiation, which is weaker.

Answer 11

The part of the thermos containing hot or cold liquids is isolated from outside air temperature by a partial vacuum. A vacuum does not provide a means for temperatures to pass through it.