弯曲_lecture(2)

教案：初中物理——弯曲问题教学目标：1. 了解弯曲现象的基本概念和特点；2. 掌握弯曲现象的成因和影响因素；3. 能够运用物理学原理分析解决实际弯曲问题；4. 培养学生的观察能力、思考能力和实践能力。

教学内容：1. 弯曲现象的定义和分类；2. 弯曲的成因和影响因素；3. 弯曲的计算和矫正方法；4. 实际弯曲问题的分析和解决。

教学过程：一、导入（5分钟）1. 引导学生观察日常生活中的弯曲现象，如弯曲的竹竿、弯曲的铁丝等；2. 提问：什么是弯曲现象？弯曲现象有哪些特点？二、新课讲解（15分钟）1. 讲解弯曲现象的定义和分类；2. 讲解弯曲的成因和影响因素，如外力作用、材料性质等；3. 讲解弯曲的计算和矫正方法，如弯曲度的测量、矫直器的使用等；4. 结合实例，讲解实际弯曲问题的分析和解决。

三、课堂讨论（15分钟）1. 学生分组讨论：你们在生活中还遇到过哪些弯曲现象？是如何解决的？2. 各组汇报讨论成果，分享经验和教训。

四、动手实践（15分钟）1. 学生分组进行弯曲实验，观察弯曲现象的成因和影响因素；2. 学生尝试使用矫直器进行弯曲矫正，掌握矫正方法；3. 学生相互交流实验心得，分享实践经验。

五、课堂小结（5分钟）1. 教师总结本节课的主要内容和知识点；2. 学生提问，教师解答疑问。

六、课后作业（课后自主完成）1. 复习本节课的内容，巩固知识点；2. 结合生活实际，思考并提出弯曲问题，尝试运用所学知识进行分析解决。

教学反思：本节课通过观察日常生活中的弯曲现象，引导学生了解弯曲现象的基本概念和特点，掌握弯曲的成因和影响因素，以及弯曲的计算和矫正方法。

通过课堂讨论和动手实践，培养学生的观察能力、思考能力和实践能力。

在教学过程中，要注意关注学生的学习反馈，及时调整教学方法和节奏，确保教学效果。

同时，注重课后作业的布置和辅导，帮助学生巩固所学知识，提高解决实际问题的能力。

托福听力tpo45 lecture1、2、3、4 原文+题目+答案+译文Lecture1 (2)原文 (2)题目 (4)答案 (6)译文 (6)Lecture2 (7)原文 (7)题目 (10)答案 (12)译文 (12)Lecture3 (15)原文 (15)题目 (17)答案 (19)译文 (19)Lecture4 (21)原文 (21)题目 (24)答案 (26)译文 (26)托福听力tpo45 lecture1、2、3、4 原文+题目+答案+译文Lecture1原文NARRATOR: Listen to part of a lecture in an art history class.MALE PROFESSOR: As I was saying, the Renaissance period—which started in the fourteen hundreds in Europe—the Renaissance was still a pretty religious period. And that's reflected in the artwork of that time.But artists were starting to experiment with a more secular point of view as well—a tendency to also use the natural world as the subject matter for their art.And there were different ways that these natural themes were explored. For instance, many artists would paint portraits, while others—although this was more common in northern Europe—would make landscapes the subject of their works.But today I'd like to consider an influential Italian Renaissance artist, Leon Battista Alberti, who took a slightly different approach.Leon Battista Alberti was a painter, sculptor, architect, musician, poet—very wide-ranging interests—like daVinci or Michelangelo, the sort of guy for whom the term “Renaissance man” was in fact created.Alberti believed that the most important approach for a painter was to capture a story or narrative. Now, as I've indicated, this narrative could be either religious or secular, depending on what the work of art was for. If the work was to be placed in a church then obviously it'd have a religious theme, whereas if it was for someone's home then it could deal with a different subject matter. The exact narrative didn't really matter, so long as it was one that captivated the audience—that held the viewer's attention.So what is actually needed to tell a story?Well, Alberti needed characters, right? Human figures.And he wanted to represent them as realistically as possible to capture the viewer's attention. One way he achieved this was to make use of what's known as the contrapposto pose.A contrapposto pose basically entails showing a slight twist in the body. The shoulders and hips are usually bent in different directions. In other words, if the left shoulder is bent so that it's slightly higher than the right shoulder, then the hips will be bent so that the left side will be slightly lower than the right side. Similarly, in sculptures, most of the weight seems to be on one foot, which also results in this slanted position—making it seem like the figure is about to walk or move. This adds to the realistic aspect of the figure.But there are actually a lot of things that could go wrong in the attempt to create such a pose. You could make a figure’s arms bigger than its legs, or the head too small for the body. Messing up the proportions can leave a figure looking cartoon-like and unnatural. But Alberti had a solution: He encouraged artists to visualize a figure's bones and structure. This would give the artist an idea of the proportions of the figure. From there, Alberti suggested the artist imagine attaching the tendons and muscles, then covering those with flesh and skin.Now, although this method may seem complicated, artists since antiquity have used anatomical observations to try to get the proportions of the human figure as accurate as possible—though obviously not to the degree that Alberti was recommending.Now, in addition to characters, the setting is extremely important, especially when attempting to tell a story realistically. Renaissance artists essentially needed to create a three-dimensional scene on a two-dimensional surface. They accomplished this by the use of perspective—a relatively new idea for artists at the time. In particular, the type of perspective that Alberti advocated was called linear one-point perspective. In fact, Alberti was one of the artists who developed the geometry behind linear one-point perspective.Linear perspective basically consists of drawing straight lines that extend from the forefront of the painting into the background—lines that seem to be parallel to each other, but which actually converge on a single point in the horizon, called the vanishing point. By drawing figures and objects smaller and smaller as the lines get closer together, the artist is able to create depth in a painting. This gives the illusion of a third dimension and makes the work of art more realistic.题目1.What is the lecture mainly about?A. Reasons for the transition from religious to secular themes in Renaissance artB. The disproportionate influence of Italian artists during the Renaissance periodC. Techniques used during the Renaissance to produce realistic works of artD. A comparison of themes in paintings and sculptures during the Renaissance2.What is the professor's opinion of Leon Battista Alberti as an artist?A. Alberti's interests were too diverse for him to succeed in any one field.B. Alberti was ineffective in imposing his own theories on other artists.C. Alberti was a much more skilled artist than da Vinci or Michelangelo.D. Alberti represents the Renaissance ideal of wide-ranging achievement.3.According to the professor, what did Alberti consider to be the most important aspect of a Renaissance painting?A. That it convey an appealing narrativeB. That its figures be posed symmetricallyC. That its theme not be religiousD. That its characters be positioned within a landscape4.Why did some artists begin to use the contrapposto pose?A. To create a cartoon-like effectB. To help viewers identify the main figure in a work of artC. To show the relative sizes of human figuresD. To make human figures appear more natural5.Why does the professor discuss tendons and muscles?A. To emphasize that Alberti's study of anatomy led to his interest in artB. To show the emphasis Alberti placed on using physically fit modelsC. To illustrate the difficulty of maintaining a contrapposto pose in real lifeD. To explain one of Alberti's methods for creating accurate proportions6.Why was the development of linear one-point perspective important to Renaissance artists?A. It helped painters to place figures more symmetrically within their paintings.B. It allowed painters to create an illusion of three dimensions.C. It enabled artists to paint large landscapes for the first time.D. It encouraged artists to take an interest in geometry.答案C D A D D B译文旁白：听一篇艺术史学科讲座。

上一种类和启录蛋白质和原为起始、的限速步重要环节我们绍一下转招募到启合在启动聚合酶II 子上，共1、 真核转1.1 启动TATA 上TFIID 是序列结合TATA BOX 统称为TB TBP 蛋白质与DNA大沟一节中我们启动子的结质编码基因原核细胞转延伸和终步骤，而对转节。

们以一个含转录前起始启动子序列动子的特定及其他通共同形成真转录的起始子的识别A box 可以是一个多亚合的那个蛋Binding P BP ‐associa 一旦结合与DNA 的沟中来实现们了解了真结构，接下因为例来看转录过程相终止三个阶转录起始含有TATA 始复合体的列之前，已定元件上，通用转录因真核转录的始别以被TFIID 通亚基的蛋蛋白我们叫Protein ，T ated facto 合到TATA 的识别结合现的，比如真核细胞中下来我们以看看真核细相同的是，阶段，起的调控也box 的启的装配过程经有一些他们可以因子，并帮的前起始复通用转录蛋白复合体叫做TATA TBP ，而TF ors ，TBP 相BOX 上，合比较常见如前面提中的RNA 以RNA 聚细胞的转录真核细胞始阶段同也是基因表启动子为例程。

在RN 些通用转录以进一步帮助他们结复合体。

录因子所识体，其中与A box 结合FIID 中的其相关因子能够使TA 见的情况是到的原核聚合酶的聚合酶II 录过程吧胞转录也分同样是转录表达调控的例，先来介NA 聚合酶录因子会结招募RNA 结合到启动识别，实际TATA box合蛋白，其它亚基TAFs 。

ATA 序列产是通过蛋白核细胞因的转。

分录的介酶结A动产生极大的白质中的一子区域4的扭曲变一个螺旋与原核启变形。

通常旋结构插入启动子‐35常入5区的识别双螺旋的TBP 个平台。

在TBP 之的相互作也就是所方向发生再接被募集到得最后两动子上，包启动子就 别，而TBP的小沟中，结与TATbo接着TFII之后被募集作用是非对所有其他蛋生。

工程背景、受力特征、变形特征、内力分布特征如何表征？—— ►变形表征►内力表征、内力图‹工程背景——钢筋混凝土框架结构楼板 次梁主 梁 柱梁在工程结构中的作用？强度考察点？Ⅰ、弯曲的概念Ⅱ、梁的计算简图 1、支座的基本形式 (1)固定端B计算简图约束反力FA A MA q0 MR FRx FRy(2)固定铰支座和可动铰支座固定铰 支座 可动铰 支座支座简图 约束反力FRAx FRAyFR B2、梁的基本形式 (1)悬臂梁FRx MR FRyF(2)简支梁FRx FRy1F 静定梁FRy2(3)外伸梁FRxFFRy1FRy2桁架桥梁承受汽车荷载的计算简图受载机车轮轴的计算简图____ 弯曲‹钢筋混凝土框架结构中的楼板导载、次梁导载楼板 次梁主 梁 柱¾楼板导载A 主梁次 梁 F次梁qB柱主 梁计算简图Ⅲ、弯曲问题的特征分析‹受力特点 杆件受到垂直于杆轴线的外力（横向力）或外力 偶（其矢量垂直于杆轴）作用。

Me MeAFB变形特征分析•梁的挠曲线•梁的弯曲挠度和截面转角•梁任一dx段的变形特征•梁任一dx段的变形特征（续2）内力分布特征•正向内力系（正应力）•切向内力系（切应力）内力分布特征•正向内力系的合力矩效果——弯矩)(x M内力分布特征内力分布特征•切向内力系的合力效果——剪力)(x F S )(x Q 或•剪力的正、负号规定•弯矩的正、负号规定M(x)M(x)Ⅱ、剪力方程和弯矩方程•剪力图和弯矩图剪力沿x 轴的大小分布图称为剪力图；)(S S x F F =)(x M M =剪力方程弯矩方程反映横截面上剪力弯矩随截面位置变化的函数式弯矩沿x 轴的大小分布图称为弯矩图。

理论上讲用截面法可确定剪力方程、弯矩方程以及剪力图、弯矩图，但…偶（支座力）作用处或分布载荷过渡处；1+=n bh ω32bh =ω内力图特性典型图例——结构对称、载荷对称时，剪力图反对称，弯矩图正对称组合结构的内力图——约束力、内力求解顺序：先求从结构，后解主结构图示AB为主结构，BC为从结构。

弯曲用英语怎么说弯曲，即不直。

可以分为形变弯曲及空间弯曲。

当杆件受到与杆轴线垂直的外力或在轴线平面内的力偶作用时，杆的轴线由原来的直线变成曲线，这种变形叫弯曲变形。

曲率处处不为零的空间称为弯曲空间。

那么你知道弯曲用英语怎么说吗?下面来学习一下吧。

弯曲英语说法1：bend弯曲英语说法2：crooked弯曲英语说法3：winding弯曲英语说法4：Warp弯曲的相关短语：弯曲力 bending force ; curve force弯曲角 bending angle ; angle of bend ; bend angle ; angularity 弯曲线 bending line ; curved line ; deflection curve ; Bend Line 过度弯曲 overbend ; over bendingoverbending纵向弯曲longitudinal bending ; buckling ; longitudinal curvature弯曲的英语例句：1. Her whole body began to buckle, unbalancing the ladder.她整个身体开始弯曲，搞得梯子倾侧起来。

2. Raise one foot, curl the toes and point the foot down-wards.抬起一只脚，弯曲脚趾，使脚尖朝下。

3. The rod bent double, the reel shrieked and ratcheted.操作杆进一步弯曲，线轴发出刺耳的吱吱声。

4. Take a comfortably wide stance and flex your knees a little.双腿适度分开站立，双膝稍稍弯曲。

5. Her spine curved.她的脊柱弯曲了。

6. Steel barriers can bend and absorb the shock.钢制栅栏可以弯曲并能吸收冲击力。