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16讲：碰撞弹性和非弹性——参照框架质量中心
Lecture 16: Collisions - Elastic and Inelastic - Center of Mass Frame of Reference |
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| 课程网址: |
http://videolectures.net/mit801f99_lewin_lec16/
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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。 1D弹性碰撞：**具有给定速度的质量在一维碰撞中与第二质量（最初处于静止状态）碰撞。动量是守恒的。如果动能也是守恒的，则可以计算碰撞后两个物体的速度。分析探讨了三个极限情况，然后进行了论证。这些方程用于预测某些航迹实验的结果。** 2。 Brain Teaser与墙壁的弹性碰撞：**网球弹性地弹出墙壁。墙的动量发生变化，但墙的动能保持为零。怎么可能？需要考虑的事情！** 3。质心（CM）参照系：**一维弹性碰撞被认为是从CM参照系（总动量为零）中看到的。使用Lab框架中CM的速度，您可以在两个框架之间进行转换。** 4。 1D非弹性碰撞和内能：**从实验室和CM框架考虑1D非弹性碰撞。在两个帧中计算动能，并且显示CM框架中的初始KE是可以转换为热量的最大KE（这被称为系统的内部能量）。这些方程用于预测空中轨道实验的结果。** 5。牛顿的摇篮示范：** Lewin教授征求他的演示的分析证明，展示了一系列碰撞球。
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| 课程简介: |
**1. 1D Elastic Collisions:** A mass with given speed collides with a second mass (initially at rest) in a one dimensional collision. Momentum is conserved. If kinetic energy is also conserved, the velocities of both objects after the collision can be calculated. Three limiting cases are explored analytically, and then demonstrated. The equations are used to predict the outcome of some air track experiments. **2. Brain Teaser - Elastic Collision with a Wall:** A tennis ball bounces off a wall elastically. The momentum of the wall changes, but the kinetic energy of the wall remains zero. How is that possible? Something to think about! **3. Center of Mass (CM) Frame of Reference:** A 1D elastic collision is considered as seen from the CM frame of reference (where the total momentum is zero). Using the velocity of the CM in the Lab frame, you can transfer between the two frames. **4. 1D Inelastic Collision and Internal Energy: ** A 1D inelastic collision is considered from the laboratory and the CM frame. The kinetic energy is calculated in both frames and it is shown that the initial KE in the CM frame is the maximum KE that can be converted to heat (this is called the internal energy of a system). The equations are used to predict the results of an air track experiment. **5. Newton's Cradle Demonstration:** Professor Lewin solicits an analytical proof of his demo showing a lineup of colliding balls.
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| 关 键 词: |
弹性碰撞; 非弹性碰撞; 内能
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| 课程来源: |
视频讲座网
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| 最后编审: |
2019-05-23：lxf
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| 阅读次数: |
67
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