作者s6414073 (狗狗)
看板Physics
標題[問題] 正負功問題
時間Thu Oct 8 03:39:58 2009
原文書詳解寫 the work done by the system on the surrounding
這句怎麼翻?
我覺得應該翻成:由系統對外作功
系統能量減少 應該是負功才對
原文書上也寫負 老師一直說是正
這題是PV功
題目如下：
A heating coil is immersed in a 100-g sample of H20 liquid at 100度C in an
open insulated beaker on a laboratory bench at 1 bar pressure. In this process
,10% of the liquid is converted to the gaseous form at a pressure of 1 bar.A
current of 2.00 A flows through the heater from a 12.0-V battery for 10^3 s to
effect the transformation. The densities of liquid and gaseous water under
these conditions are 997 and 0.590 kg/m^3 ,respectly.
Calculate q and w for the process.
計算..大家應該都會
只是正負號令我很納悶...
麻煩大家幫個忙..感激不盡..>Q<
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◆ From: 120.105.155.89
※ 編輯: s6414073 來自: 120.105.155.89 (10/08 03:43)
1F：推 denisck123:會不會是定義問題 有些人會訂為對系統做的功 10/08 08:22
2F：→ denisck123:有些人士訂為系統對外做的功 10/08 08:22
3F：→ grind:系統對外界作正功...故外界得能量... 10/08 10:44
4F：→ grind:外界對系統作負功...故系統損失能量... 10/08 10:45