A bath is filled up by a hot water tap and a cold water tap. Hot water at 70 degree is poured at a rate of 0.1kg per second while cold water at 20 degree fills the bath at a rate of 0.14kg per second.The two taps are turned on at same time.The cold water tap is turned off after 2 minutes , and 3 minutes later the cold water tap also stopped. (Given: Specific heat capacity of water = 4200 JKG^-1degree^-1)
a) Find the mass of water in the bath.
b)Assume 10% of heat released by the hot water is lost to the surrondings.Find the final water temperature of the bath.
f.4 Phy Heat
2009-10-23 5:20 am
回答 (3)
2009-10-23 6:07 am
✔ 最佳答案
(a) Mass of hot water = 0.1 x (5 x 60) kg = 30 kgMass of cold water = 0.14 x 2 x 60 kg = 16.8 kg
Total mass of water in the bath = (30+16.8) kg = 46.8 kg
(b) Let T be the final water temperature
Heat absorbed by cold water = 16.8 x 4200 x (T-20) J
Healt given out by hot water = 30 x 4200 x (70-T) J
Since only 90% of the heat given out by the hot water is absorbed by the cold water, hence,
[30 x 4200 x (70-T)] x 0.9 = 16.8 x 4200 x (T-20)
solve for T
2009-10-23 6:39 am
sorry,I type wrong that you remind me before.
''Hot'' is not ''cold''
''Hot'' is not ''cold''
2009-10-23 5:59 am
The "cold" water tap is turned off after 2 minutes , and 3 minutes later the "cold" water tap also stopped.
Which one is turned off first ?
Which one is turned off first ?
收錄日期: 2021-04-29 17:32:25
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