(1)an electric kettle of heat capacity 420JC^-1 contains 0.9 kg of water at 20C.When the kettle has been switched on for 240s,the water starts boil.Estimate the power of the heating element.(the specific heat capacity of water is 4200 J kg^-1 C^-1) 唔識做呢條數,有冇人幫到我?
(2)同埋mist 形成係 can of cold drink度算唔算係evaporation?
(3)點解水唔適合做溫度計?
物理熱學,3條問題!!
2008-10-28 4:33 am
回答 (4)
2008-10-28 6:40 am
✔ 最佳答案
1) power = [420(100-20)+0.9*4200(100-20)]/240s = 1400 W(我想問electric kettle 有冇weight ga??)
2) dunno
3)唔適合,,因為water expaneds at near ice pt. i.e. 4'C
2008-10-27 22:41:24 補充：
因為water expands at near ice pt. i.e. 4'C
2008-10-28 6:54 am
1 唔答,功課自已慢慢做,再唔識下次先答你
2 唔係evaporation, 係condensation
3 唔適合, 因水的膨脹係數唔夠線性,尤其是4度C。
重有水係萬物之源,容易滋生細菌,生虫,發臭,如果加消毒水,又唔知個膨脹係數係咩，所以唔用。OK?
2 唔係evaporation, 係condensation
3 唔適合, 因水的膨脹係數唔夠線性,尤其是4度C。
重有水係萬物之源,容易滋生細菌,生虫,發臭,如果加消毒水,又唔知個膨脹係數係咩，所以唔用。OK?
2008-10-28 4:53 am
1)水銀張力比水大（水銀滴到地上會變成球狀）
2)水銀(Hg)不是液態鐵(Fe)
別亂講= =
2)水銀(Hg)不是液態鐵(Fe)
別亂講= =
2008-10-28 4:38 am
幫你答3,因為水既脹力太大,如果用水黎做溫度計的話~個溫度計會好大,為左方便,液態鐵~即係水銀~~係最理想既物質
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