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9讲：考试复习1
Lecture 9: Exam Review 1 |
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| 课程网址: |
http://videolectures.net/mit801f99_lewin_lec09/
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| 主讲教师: |
Walter H. G. Lewin
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| 开课单位: |
麻省理工学院
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| 开课时间: |
2008-10-10
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| 课程语种: |
英语
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| 中文简介: |
** 1。缩放参数：**如果母亲保护大型动物的股骨免受挤压，股骨的横截面积应随着质量而扩大。但事实并非如此。股骨的直径与其长度成比例。这可以保护股骨免受屈曲（侧向变形）。 ** 2。点产品：**通过分解和投影，审查了两种获得标量积的方法。 ** 3。交叉乘积：**交叉乘积的大小等于两个向量的大小与它们之间角度的正弦的乘积。使用右手开瓶器规则确定矢量乘积的方向。 ** 4。 1D运动学：**给出位置x（t）的图形示例，并且在各个时间点导出速度和加速度。计算平均速度和平均速度。构建了速度与时间的关系图。 ** 5。轨迹：**轨迹在一架飞机上;因此，它们减少到二维问题。使用“零重力”轨迹的轨迹来工作一个详细的例子。在KC135中进行的实验（见第7讲）。 ** 6。均匀圆周运动：**回顾了均匀（恒速）圆周运动的参数，包括角速度和向心加速度的方程。制定出来的数值例子是美国宇航局用于测试宇航员的离心机;向心加速度约为10g！ ** 7。带标尺的脑筋急转弯：** Lewin教授将手指滑到一个标尺下方，朝向中心。奇怪的事情发生了，手指似乎轮流移动，他们交替滑动和停止。你能解释一下吗？
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| 课程简介: |
**1. Scaling Arguments:** The cross-sectional area of femurs should scale with mass if mother nature were protecting the femurs of large animals from crushing. But that is not the case. The diameter of a femur scales with its length. That protects the femurs against buckling (sideways deformation). **2. Dot Products:** Two methods are reviewed for obtaining the scalar product, by decomposition and by projection. **3. Cross Products:** The magnitude of the cross product equals the product of the magnitude of the two vectors and the sine of the angle between them. The direction of the vector product is determined using the right-hand corkscrew rule. **4. 1D Kinematics:** A graphic example of the position x(t) is given, and the velocity and acceleration are derived at various points in time. The average velocity and average speed are calculated. A plot of velocity vs. time is constructed. **5. Trajectories:** Trajectories lie in a plane; they therefore reduce to 2 dimensional problems. A detailed example is worked using the trajectory of the "zero gravity" experiments in the KC135 (see Lecture 7). **6. Uniform Circular Motion:** The parameters for uniform (constant speed) circular motion are reviewed, including the equations for angular velocity and centripetal acceleration. The numerical example worked out is NASA's centrifuge to test astronauts; the centripetal acceleration is about 10g! **7. Brain Teaser with a Yardstick:** Professor Lewin slides his fingers underneath a yardstick, towards the center. Something strange happens, the fingers seem to take turns moving, they alternate sliding and stopping. Can you explain this?
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| 关 键 词: |
缩放参数; 网络产品; 跨产品; 一维运动; 轨迹
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| 课程来源: |
视频讲座网
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| 最后编审: |
2020-06-01：吴雨秋(课程编辑志愿者)
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| 阅读次数: |
39
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