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InterviewSolution
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Indian style of cooling drinking water is to kept it is a pitcher having porous walls water comes to the outer surface very alowly and evaporates .Most of the itself and the water is cooles down .Assums that a pitcher containe `10kg` water and `0.2g` of water comes from the itomsphere decrease by ``5^(@)C` specific beat capicity of water` = 4200J kg^(-1)^(@)C^(-1)` and letent head of vaporization of water `= 2.27 xx 10^(6)J kg^(-1)` |
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Answer» Energy required to decreases the temp of `10kg` of water to `5^(@)C` `U = 10 xx 4200J//kg^(@)C xx 5^(@)C` `= 210.000 = 21 xx 10^(6)J` `Energy required to for evaporation of water to `0.2kg//sec` `= 2 xx 10^(-4) xx 2.27 xx 10^(6)` = 454` `454J` energy losing system per second `= (21 xx 10^(4))/(454)` `21 xx 10^(4)J`energy losing system during one minute `= (21 xx 10^(4))/(454 xx 60) = 7.7 minute` The time required to decrease temp by `5^(@)C is 7.7 minute` |
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