作者s6414073 (狗狗)
看板Physics
标题[问题] 正负功问题
时间Thu Oct 8 03:39:58 2009
原文书详解写 the work done by the system on the surrounding
这句怎麽翻?
我觉得应该翻成:由系统对外作功
系统能量减少 应该是负功才对
原文书上也写负 老师一直说是正
这题是PV功
题目如下：
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.
计算..大家应该都会
只是正负号令我很纳闷...
麻烦大家帮个忙..感激不尽..>Q<
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◆ From: 120.105.155.89
※ 编辑: s6414073 来自: 120.105.155.89 (10/08 03:43)
1F：推 denisck123:会不会是定义问题 有些人会订为对系统做的功 10/08 08:22
2F：→ denisck123:有些人士订为系统对外做的功 10/08 08:22
3F：→ grind:系统对外界作正功...故外界得能量... 10/08 10:44
4F：→ grind:外界对系统作负功...故系统损失能量... 10/08 10:45