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(2011-05-20 14:27)

### 杂谈

Minhua Chen

Keyan Middle School,Shaoxing County, Zhejiang Province, People’s Republic of China

All physical quantities for which a continuity equation can be written are called substance-like quantities.1,2 Such quantities include, for example, electric charge, momentum(linear or angular), entropy, and the like. The method of presentation remains much the same from one sub-branch of physics to another, for these quantities have something in common: namely, each can be thought to be contained in a physical system and flow from one system to another. Thus knowledge of a single branch of physics already provides an analogy for the ways and means by which processes are described in other branches.

(2011-05-20 14:11)

### 杂谈

摘要：当前流行着各种各样的重力的定义。这些定义在重力和相关概念（如失重）的教学中会出现混乱。运用动量流的概念，我们找到了一种新的重力的定义。它可以避免这种混乱。

关键词：重力；定义；实物型物理量；动量流

重力是一个变化中的概念。我们可以从国内外文献中找到各种各样的对重力的定义的表述。在美国物理教师协会（AAPT）的两本杂志《美国物理学杂志》和《物理教师》中，我们发现，早在上世纪六十年代初就开始有这方面的争论了,并一直持续到现在。最近，我国的一些学者在《物理教学》、《物理通报》等杂志上也在讨论这个问题。我们可以将这些不同的重力的定义分为两大类：第一类是把作用在物体上的万有引力定义为重力，这种重力的定义叫做万有引力定义（gravitational definition）；第二类是把用重力测量仪的示数或物体对支持物（或悬挂物）的力定义为重力，这种重力的定义叫做操作型定义（operational definition）。这两种定义有一个共同的特点，即它们都与力的概念有关。

&

(2011-05-20 12:12)

### 杂谈

Minhua Chen, Keqiao High School, Shaoxing, Zhejiang, China

Weight is a changing concept in physics. There are various definitions of weight. They can be divided mainly into two kinds: one identifies weight with the gravitational force exerted on a body and is called a gravitational definition; the other associates weight with the result of weighing, or the supporting force, and is called an operational definition. These definitions of weight refer to the concept of force. According to Einstein’s epistemology, physical theories (as well as physical concepts) are built psychologically upon the experiences of the world of perceptions. However, what we feel is not the force but something different, namely stress or, equivalently, the flow of momentum through our bodies. For example, if we hang from a cross bar, the force on us is zero but the momentum current through us is not. A

(2011-05-20 11:58)

### 与作者在德国

由我翻译的德国卡尔斯鲁厄物理课程1-3册和教师用书于2007年由上海教育出版社出版，由我改编的德国卡尔斯鲁厄物理课程《波动与信息》于2009年由上海教育出版社出版。

这一课程在20世纪80年代由德国卡尔斯鲁厄大学物理教学研究所开发，主要作者是F.Herrmann教授。

这一课程的特点从根本上来说基于以下两个观点：

1.抛开了许多历史的负担。

(2011-05-19 13:31)

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