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1 Primary & Middle School Physics1–9 年级在线 2 High School Physics10–12 年级在线 3 University Physics — Year 1本科一年级在线 4 University Physics — Year 2本科二年级在线 5 University Physics — Year 3本科三年级在线

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1 Markets I: The Ecosystem and Exchange-Traded Markets市场在线 2 Markets II: Rates, FX and Credit市场在线 3 Markets III: Commodities, Energy and Crypto市场在线 4 Quantitative Methods方法在线 5 Derivatives and Volatility衍生品在线 6 Rates, Credit, XVA and Risk利率、信用与风险在线 7 Research Craft: Predictors, Backtests, Measurement, Portfolios研究在线 8 Strategies I: Equities and Futures策略在线 9 Strategies II: Volatility, Relative Value, Macro and the Bank Desks策略在线 10 Microstructure and Execution交易执行在线 11 Market Making and High-Frequency Trading做市在线 12 Machine Learning for Markets机器学习在线 13 Low-Latency Software技术在线 14 Networks, Hardware and Trading Infrastructure技术在线 15 Research, Data and Risk Platforms技术在线 16 The Desk and the Firm公司运营在线 17 The Industry: Firms, Roles and Careers职业发展在线 18 Interviews I: Maths, Probability and Speed职业发展在线 19 Interviews II: Markets, Trading Games and the Final Round职业发展在线 20 Interviews III: Code职业发展在线

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Physics · 术语表

什么是 Center of mass？

Definition 16.1 High School Physics · 第 16 章 — Forces and Motion

The center of mass of a body or system is its balance point — the average position of its mass: the geometric center of a homogeneous symmetric body; for two point masses, the point of the joining segment at distances in the inverse ratio of the masses, $\frac{d_1}{d_2} = \frac{m_2}{m_1}$ — closer to the heavier.

A thrown wrench at equal time intervals: the wrench spins, but its center of mass (dots) rides a plain parabola.

示例

Example 16.2 (A lopsided dumbbell)

Balls of $2.0\,\mathrm{kg}$ and $1.0\,\mathrm{kg}$ sit at the ends of a light bar $0.90\,\mathrm{m}$ long. The center of mass divides it in the inverse ratio $d_1/d_2 = 1.0/2.0$ : $0.30\,\mathrm{m}$ from the heavy ball, $0.60\,\mathrm{m}$ from the light one — balance the bar there.

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