CrazyEngineers Archive
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@m.vivekanandan • 28 May, 2012 • 1 like

The hot water kept in well insulated thermos flask is an example of closed system or isolated system??

@Ramani Aswath • 28 May, 2012 • 2 likes Depends.
In theory it is an isolated system. In reality it is a closed system as mass transfer is prevented. Unless the temperature of the water remains invariant with time it cannot be an isolated system as heat transfer, albeit slowly, still takes place.
@akash.kasina • 30 May, 2012 theoretically,it cannot be a closed system because in an insulated thermos flask,neither matter,nor energy is transferred.....so it's an example of isolated system,but under practical considerations the container cannot be a perfect insulator of heat...right!!!!
so it's a closed system practically.😁👍
@nibhani • 03 Jun, 2012 • 1 like
m.vivekanandan
hot water kept in well insulated thermos flak is an example of closed system or isolated system??
it is a closed system because it will transfer heat with surrounding but not transfer mass so it is a closed system...
@mechky • 03 Jun, 2012
m.vivekanandan
hot water kept in well insulated thermos flak is an example of closed system or isolated system??
In a closed system, no mass transfer takes place across the boundaries. Whereas in case of isolated system, neither mass nor energy transfer occurs across the system boundaries.

So, as bioramani sir said, in reality it is always a closed system as no transfer of mass(water) is taking place. Isolated systems do not exist in reality.
@zaveri • 03 Jun, 2012 • 1 like
nibhani
it is a closed system because it will transfer heat with surrounding but not transfer mass so it is a closed system...
how can heat transfer take place through an insulated medium ?
@akash.kasina • 03 Jun, 2012
nibhani
it is a closed system because it will transfer heat with surrounding but not transfer mass so it is a closed system...
assuming the thermos as 100% ideal,heat cannot be exchanged,even practically very small amount is exchanged,thats the reason why we use thermos flasks!!😀
@mechky • 04 Jun, 2012
zaveri
how can heat transfer take place through an insulated medium ?
akash.kasina
assuming the thermos as 100% ideal,heat cannot be exchanged,even practically very small amount is exchanged,thats the reason why we use thermos flasks!!😀
Considering a real situation, heat transfer takes place across an insulated thermos flask. I am not aware of any flask in which you can put something warm and it will remain at that temperature forever. So indeed it is a closed system.

However if we assume ideal situations, we can consider it to be a isolated system.
@nibhani • 07 Jun, 2012
zaveri
how can heat transfer take place through an insulated medium ?
heat transfer can't takes place through an insulated meadium..but in practical life perfectly insulated meadium is not possible...
@m.vivekanandan • 11 Jun, 2012 if this question is asked in exam , i will go with isolated system??
@vikaskumar11233 • 11 Jun, 2012 According to me it is a closed system.As the mass is not transferred.
@Ramani Aswath • 11 Jun, 2012
m.vivekanandan
if this question is asked in exam , i will go with isolated system??
If I were the examiner, I would mark it wrong. No vacuum flask is completely insulating.
@nibhani • 12 Jun, 2012
m.vivekanandan
if this question is asked in exam , i will go with isolated system??
if this question will be asked in exam you can give the same answer which i have given because it is an actual answer no one can say that its wrong...u can feel it in practical life...
@nibhani • 12 Jun, 2012
m.vivekanandan
hot water kept in well insulated thermos flak is an example of closed system or isolated system??
in ideal case it is an example of isolated system...but in practiacal case it is an example of a closed system because fask is well insulated not perfectly insulated....and perfectly insulaated system is not possible in this world..so ideally u can say that it is an isolated syastem but not practiaclly...
@mechky • 12 Jun, 2012
m.vivekanandan
if this question is asked in exam , i will go with isolated system??
Yes, theoretically we assume it to be isolated system.
@Kedar Malwadkar • 25 Jun, 2012 theoreticaly it is example of isolated system.
@The myth buster • 25 Jun, 2012 • 1 like the answer is "closed system"..becoz their is nothing like a perfect insulator..so some transit energy in the form of heat shall always be there..due to this heat interaction between the system(water jar) and the surrounding,the system cannot be justifiably called as an isolated system.
@Ankita Katdare • 23 Jan, 2020

If the system allows neither energy or matter transfer, then it is an isolated system. With time I think anything (be it ice or hot tea) kept in a commercially made thermos flask will emit energy and become cooler or hotter according to surrounding temperature. This would mean, hot water kept inside a thermos flash is an example of a 'closed system'.

@bill yorke • 23 Jan, 2020

I have to admit this in confusing but I believe it is a closed system but not an isolated system. Thermos flask consists of a vacuum spacing, shinny internal surface as well as rubber cap and support to limit heat loss by convection, radiation and conduction. This aids to maintain a relatively constant temperature of the content against the external environment by modifying the immediate surrounding environment.

If the system was such that it is applicable in a strictly regulated environment in addition to the container modifications itself then I would agree it is an isolated system. But, that seems not the case.

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