关于滑动摩擦力做功的问题

众所周知,恒力做功的公式为W=Fscosθ,这里s是受力物体(质点)的位移,这本来都很清楚已不成问题,但是,一旦涉及到一个物体在另一个物体表面上滑行有滑动摩擦力做功时,关于功的公式中的位移s应作何理解,却激起了极大的争议.近日先后出现了几篇涉及同一内容的文章,认为在滑动摩擦力做功时,公式中的s不能与其他情况下的位移同样理解,而必须另作定义.笔者仔细地看了这几篇文章,觉得还是应该     

再论滑动摩擦力做功的问题

本刊2005年第2期刊登了一篇题为《滑动摩擦力做功问题再探》的文章（下称郑文），该文针对笔者2003年写的《关于滑动摩擦力做功的问题》（载于本刊2004年第1期）一文，提出了尖锐的反驳意见,笔者反复认真拜读以后，颇有感想和启发，踌躇再三，我还是走向书桌，打开了电脑……     

浅议滑动摩擦力做功W=fs中的“s”

滑动摩擦力做功是普通物理教学中的重点和难点,笔者从3个方面阐述了滑动摩擦力做功的公式W=fs中“s”的含义.既是对摩擦力内容的重要补充,也是对做功问题的升华.仅抒己见,希望对普通物理的教学有所帮助.     

滑动摩擦力做功的特点

1．滑动摩擦力可以做正功、负功或不做功． 如图1,将物体轻放在匀速传动的传送带上,在物体速度达到与传动速度相等之前,物体与传送带之间有相对滑动,滑动摩擦力对物体做正功,对传送带做负功．若使物体以一定的速度滑上静止的传送带,则滑动摩擦力对物体做负功,对传送带不做功．     

摩擦力作功的一个佯谬

运动的汽车,受着地面给它的摩擦力作用,并在摩擦力作用下沿摩擦力的方向运动了一段位移。摩擦力对运动的汽车是否作功？本文从体动力角度和功的定义这一基本概念出发,分析了摩擦力对运动的汽车并不作功,但摩擦力却起到将汽车发动机中的内能转化为运动汽车的动能的作用。     

滑动摩擦力探析

力学中常见的几种力中,滑动摩擦力(以下简称摩擦力)的计算容易发生错误,这是因为摩擦力方向的判定和计算方法都由具体问题确定.本文就这两个问题进行探析。     

滑动摩擦力方向的判定

小船渡河历来是运动的合成与分解方面的典型例子．利用它的结论可以解决滑动摩擦力的方向问题．     

研究滑动摩擦力的实验

1装置介绍 (1)用验证牛顿第二定律的木板作底座,中间竖直固定一块长木板,用来固定定滑轮和测力计. (2)在竖直固定的木板上端打一个孔,安装一根水平木杆,用来固定测力计.用水平木杆可以用来调节测     

滑动摩擦力做功的若干问题

一、滑动摩擦力做功与路程有关：由于滑动摩擦力的方向总是与物体的相对运动方向相反,阻碍物体的相对运动,当物体沿着固定的接触面运动时,滑动摩擦力做功与运动的路程有关．     

滑动摩擦力做功问题再探

对于本刊2004年第1期刊登的《关于滑动摩擦力做功的问题》(以下称文[1])，笔者认为有必要指出这篇文章中所存在的问题，因为这些问题根深蒂固地存在于高中物理教学中．     

滑动摩擦力演示仪的制作

滑动摩擦力演示仪，有些学校配置，但演示效果并不理想．笔者根据本刊2003年第10期《研究滑动摩擦力的实验》一文中的实验装置图，并做适当的改进，制作成滑动摩擦力演示仪，使用方便、演示效果理想，能顺利地完成教学任务．其装置如图1所示．     

双质点摩擦滑移隔震结构非线性分析

采用小波变换方法分析了双质点摩擦滑移隔震结构时频特性,结果表明：摩擦滑移隔震结构的动力特性与其运动形态有关,隔震层摩擦系数的改变对结构频率非线性影响较小,对阻尼非线性影响较大.     

对中职学生实施创业教育实践

创业教育以创业能力培养为核心,以全面提高素质为基础的系统工程.对中职学生实施创业教育是一个新的课题,要达到预期的效果,必须围绕培养目标整体设计教育内容和方法,建立有效的教育体制和运行模式.我们在这方面进行了初步实践,取得了一定的成效.     

Learning in physics by doing laboratory work: towards a new conceptual framework

Drawing on a study that explores university students’ experiences of doing laboratory work in physics, this article outlines a proposed conceptual framework for extending the exploration of the gendered experience of learning. In this framework situated cognition and post‐structural gender theory are merged together. By drawing on data that aim at exploring the gendered experience of learning in physics in the laboratory setting, a case is made for the proposed conceptual framework to facilitate an analysis of gender as an active process that relates the dynamics of this process to the emerging physicist identities of the students. In other words, this framework allows for an analysis of the gendered learning experiences in a context such as physics education that goes well beyond the usual ‘women‐friendly’ teaching approaches.     

做好高职贫困生工作的几点思考

随着我国高等职业技术学校招生规模的逐年扩大,以及高等教育成本的逐步提高,我国高等职业技术学校贫困生数量也日益增多,贫困生的问题也随之凸显出来,成为令人关注的社会问题。国家、社会和高校都采取了一系列的措施,进行了积极的探索,在我国初步形成了以“奖、贷、助、补、免”为主体的贫困大学生的资助体系,这一体系对于解决我国贫困生就学问题起到了非常重要的作用。目前全国高校中经济困难学生占在校生总数的15-30％,其中经济特别困难学生所占比例为8～15％,高职院校贫困生的比例更大。因此做好贫困生的工作成为高职院校发展的一大课题。     

The cultural interface tension: doing Indigenous work in the academy

This article explores Vanessa Anthony-Stevens and Sammy Matsaw’s paper “The productive uncertainty of Indigenous and decolonizing methodologies in the preparation of interdisciplinary STEM researchers”. That paper reports on a small qualitative study on how STEM students in the field of natural resources management react to the inclusion of Indigenous ways of knowing in their interdisciplinary research methodologies course. The authors are engaging contested intersections of knowledge that are notoriously difficult to negotiate. I argue that the inclusion of Indigenous ‘ways of knowing’ into the water resource management curriculum is based on Morgan’s (in: McKinley, Smith (eds) Handbook of indigenous education, Springer, Singapore, pp 111–128, 2019. https://doi.org/10.1007/978-981-10-3899-0) idea of the ‘guest paradigm’. At the same time, and in contrast, I also argue that the inclusion of Indigenous knowledge in the curriculum cannot just occur in the classroom but needs to be considered at an institutional and individual level as well. The project should be seen as a small step within a wider Indigenous agenda of decolonizing the Eurocentric curriculum.

     

A paradox of learning

Adult education in South Korea has been faced with rapid change under globalization since the 1990s. This article tries to describe the current situation of South Korean adult education and to point out emerging problems. Many problems experienced in South Korea are appearing in other countries, as some of them have been caused by globalization. Therefore, international co-operation is required to resolve those problems and deal with the future of adult education.     

The work of women teachers in primary literacy education: knowing and doing

This paper provides a retrospective account of three decades of my work as a literacy educator and researcher. Taking key insights from feminist sociologist, Dorothy Smith, including women's standpoint, the everyday world as problematic, institutional capture, a sociology for the people, I revisit my research on literacy, poverty and schooling. I argue that understanding better the effects of what we do in educational institutions, through collaborative research with teachers, can lead us to generate positive alternative equity‐driven practices.