The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by
convection
conduction
radiation
evaporation
Explanation
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convection is the transfer of heat in fluids from a hotter region to a cooler region, so it is made airtight to reduce the heat lost by convection of heat through air
wetin be shoro niyen he is jst sayin wot he feels ,....,......... its convection bcos fluids are nt only liquids in physics they are both liquids n gases
the answer is both convection and evaporation "BUT" the main answer there is convection this is because in the flask the cork stopper (the cover) dose not allow gas or fluid to leave it and we know that hot air would rise from the food and try to escape but it would only settle at the top and get cold and this process is known as convection
The answer is correct. For reference pls check Senior Secondary Physics, page 31
The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by **convection**.
Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids. In a vacuum flask, if the cover is not airtight, the hot or cold substance inside the flask could lose or gain heat through convection to the surrounding air.
So, the correct answer is:
**A. convection**.
The correct answer is D(covection)because stopper prevents the heat loss by convection because it is tightly sealed.
In a vacuum, there is the absence of Air ...
Hence, convection isnt possible, since there wont be a carrier of heat... in these case, should be Air
The answer is Evaporation
yes, it is made air tight to prevent heat loss through convection
but the main plastic cork prevents heat loss through conduction because the plastic is an insulator and so doesnt conduct heat
# Answer
The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by *convection*.
# Explanation
1. *Vacuum insulation*: the vacuum between the inner and outer walls of the flask reduces heat transfer by conduction and convection.
2. *Airtight cover*: the airtight cover prevents air from entering or leaving the flask, minimizing convective heat loss.
By preventing convection, the airtight cover helps to maintain the temperature of the liquid inside the flask.
u guys are saying it's evaporation...wait did the question specify whether it's liquid that's inside. u guys should first understand the question before interpreting inorder to understand what the question is getting at. conduction can be defined as the process of transferring heat from a hotter region to a colder region either through air or water. anything could be inside that vacuum that generate heat energy,in this case the vacuum is closed tightly to prevent the heat from it transferring to a colder region,the vacuum is the hotter region in this case definitely the answer in convection.
evaporation deals with liquid and the question never specified whether a particular hot liquid was present in the vacuum.
understand before interpreting a question...this has made many students fail exams. byeeeee
the answer is A. There are two corks in a flask, one at the bottom and one at the top. The top cork reduces by convection and the insulating cork at the base by conduction through the body
The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by convection. A vacuum flask works by minimizing heat transfer through all methods, but especially by eliminating convection currents in the air, which are a significant cause of heat loss in traditional containers. So, the correct answer is A. convection.
