Molecular Gas in NUclei of GAlaxies (NUGA) IX. The decoupled bars and gas inflow in NGC 278

施勇1980年11月出生。

南京大学 天文与空间科学学院email: yong@教育经历： 1999.9-­‐2003.7 北京大学，地球物理系，天文专业，学士学位。

2003.8-­‐2008.8 亚利桑那大学（美国），天文学，博士学位。

工作经历： 2008.8-­‐2009.8： 亚利桑那大学（美国），博士后。

2009.9-­‐2013.2: 加州理工学院（美国），博士后。

2013.3至今： 南京大学，教授，博导，国家青年千人。

科研基金项目：国家自然科学基金面上项目，11373021，极端贫金属星系：尘埃特性和恒星形成，2014/01-2017/12，80 万元，在研，主持。

中国科学院战略性先导B专项，XDB09000000, 宇宙结构起源B类先导，2014/01-至今，66万，在研，参与（骨干成员）。

中央组织部青年千人项目（第四批）,2013.1-2015.12, 200万，在研、主持。

江苏省基金杰出青年项目，BK20150014, 2015.7-2018.7, 100万，在研、主持。

空间望远镜项目： • P I o n H erschel O T2 y shi 3 (16.1 h rs, p riority 1):“Extremely-­‐metal p oor g alaxies: m apping d ust e mission”• T echnical C ontact a nd C o-­‐I o n S pitzer-­‐50507, 50508 (14.2 h rs, P I: G. R ieke)“Quasar a nd U LIRG E volution”• T echnical C ontact∗ a nd C o-­‐I o n S pitzer-­‐50196 (25.1 h rs, P I: G. R ieke.):“Cosmic Evolution of Star Formation in Quasar Hosts from z=1 to the Present”• T echnical C ontact∗ a nd C o-­‐I o n S pitzer-­‐40385 (2.1 h rs, P I: G. R ieke.):“A C hallenge t o t he U nification M odel”地面望远镜项目：• K eck 10 m: D EIMOS• I RAM 30 m: 24 h rs (2014A), 59.5 h rs (2016A).• P alomar 200 i nch: D BSP; L FC; W IRC• C FHT: M egaCAM• B ok 2.3 m• A rizona R adio O bservatory N RAO-­‐12m• A rizona R adio O bservatory S MT-­‐10m学术服务：ApJ, A pJL, A&A, A J, S ciChina, R AA的审稿人Telescope A ccess P rogram 望远镜分配委员会委员论文发表情况汇总（共36篇）通讯作者 非通讯作者 总计Nature 1 0 1Nature子刊 0 1 117 18 35ApJ, ApJS, ApJL,MNRAS, A&A(全部为NatureIndex高影响力科学期刊)AJ 0 1 1总计 18 20 38第一或通讯作者论文： 18. Zhang, Z.; Shi, Y* et al. 2016, ApJL, 819, 27“Distributions of quasar hosts on the galaxy main-sequence plane”17. Zhou, L.; Shi, Y* et al. 2016, MNRAS, 458, 772“Spatially resolved dust emission of extremely metal poor galaxies”16. S hi, Y.*, W ang, J., Z hang, Z.-­‐Y. e t a l. 2015, A pJL, 804, 11“The Weak Carbon Monoxide Emission in an Extremely Metal-­‐poor Galaxy, Sextans A”15. S hi, Y.*, A rmus, L., H elou, G. e t a l. 2014, N ature, 514, 335–338“Inefficient s tar f ormation i n e xtremely m etal p oor g alaxies”14. Shi, Y.*, Rieke, G., Ogle, P. et al., 2014, ApJS, 214, 23 “Infrared spectra and photometry o f c omplete s amples o f P G a nd 2MASS q uasars”13. Shi, Y.*, Helou, G., Armus, L. 2013, ApJ, 777, 6 “A Joint Model Of X-­‐ray And Infrared B ackgrounds. I I. C ompton-­‐Thick A GN A bundance”12. Shi, Y.*, Helou, G., et al. 2013, ApJ, 764, 28 “A Joint Model of the X-­‐Ray and Infrared E xtragalactic B ackgrounds. I. M odel C onstruc-­‐ t ion a nd F irst R esults”11. Shi, Y.*, Helou, G., et al. 2011, ApJ, 733, 87 “Extended Schmidt Law: Roles Of Existing S tars I n C urrent S tar F ormation”10. Shi, Y.*, Rieke, G. H., et al. 2010, ApJ, 714, 115 “Unobscured Type 2 Active Galactic N uclei”9. Shi, Y.*, Rieke, G. H., et al. 2009, ApJ, 703, 1107 “Cosmic Evolution of Star Formation i n T ype-­‐1 Q uasar H osts S ince z = 1”8. Shi, Y.*, Rieke, G. H., et al. 2009, ApJ, 697, 1764 “Role of Major Mergers In Cosmic S tar F ormation E volution”7. Shi, Y.*, Rieke, G. H. et al. 2008, ApJ, 688, 794 “BH Accretion in Low-­‐Mass Galaxies S ince z∼1”6. Shi, Y.*, Ogle, P., Rieke, G. H. et al. 2007, ApJ, 669, 841 “Aromatic Features in AGN: S tar-­‐Forming I nfrared L uminosity F unction o f A GN H ost G alaxies”5. Shi, Y.*, Rieke, G. H., Hines, D. C. et al. 2007, ApJ, 655, 781 “Thermal and Nonthermal I nfrared E mission f rom M87”4. Shi, Y.*, Rieke, G. H., Hines, D. C. et al. 2006, ApJ, 653, 127 “9.7 um Silicate Features i n A ctive G alactic N uclei: N ew I nsights i nto U nification M odels”3. Shi, Y.*, Rieke, G. H., Papovich, C. et al. 2006, ApJ, 645, 199 “Morphology of Spitzer 24 u m D etected G alaxies i n t he U DF: T he L inks b etween S tar F or-­‐ m ation and G alaxy M orphology”2. Shi, Y.*, Rieke, G. H., Hines, D. C. et al. 2005, ApJ, 629, 88 “Far-­‐Infrared Observations o f R adio Q uasars a nd F R I I R adio G alaxies”1.Shi, Y., & Xu, R. X.* 2003, ApJ, 596, 75 “Can the Age Discrepancies of NeutronStars B e C ircumvented b y a n A ccretion-­‐assisted T orque?”其他作者论文：20. G uo R. e t a l. (Shi Y. 5th a uthor), 2016, A pJ a ccepted, a rXiv:1604.0712219. Chen, Y. et al. (Shi Y. 4th author), 2016, MNRAS accepted, “Boxy Hα EmissionProfiles i n S tar-­‐Forming G alaxies”18. Bian, W. H. et al. (Shi Y. 4th author), 2016, MNRAS, 456, 4081, “Spectral principal component analysis of mid-infrared spectra of a sample of PG QSOs”17. Wang, J. et al. (Shi Y. 4th author), 2016, MNRAS, 455, 3986, “Dense-gas properties in Arp 220 revealed by isotopologue lines”16. Wang, J. et al. (Shi Y. 7th author), 2014, Nature Communication, 5, 5449 “SiO and C H3OH m ega-­‐masers i n N GC 1068”15. Kirkpatrick, A. et al. (Shi Y. 10th author) , 2014, ApJ, 796, 135 “Early Science with the Large Millimeter Telescope: Exploring the Effect of AGN Activity on the Relationships b etween M olecular G as, D ust, a nd S tar F ormation”14. Wang, J. et al. et al. (Shi Y. 4th author) , 2014, ApJ, 796, 57 “Isotopologues o f Dense G as T racers i n N GC 1068”13. Jin, S. et al. (Shi Y. 4th author), 2014, ApJ, 787, 63 “Color-­‐Magnitude Distribution o f F ace-­‐on n earby G alaxies i n S loan D igital S ky S urvey D R7”12. D ale, D. e t a l. (Shi Y. 6th a uthor), 2014, A pJ, 784, 83 “A T wo-­‐parameter M odel for the Infrared/Submillimeter/Radio Spectral Energy Distributions of Galaxies and A ctive G alactic N uclei”11. Wang, J. et al. (Shi Y. 3rd author), 2013, ApJL, 778, 39 “A SiO 2-­‐1 Survey toward G as-­‐rich A ctive G alaxies”10. Magdis, G. E. et al. (Shi Y. 22th author), 2013, A&A, 558, 136 “Mid-­‐ to far infrared p roperties o f s tar-­‐forming g alaxies a nd a ctive g alactic n uclei”9. Kim, Ji Hoon, et al. (Shi Y. 16th author), 2012, ApJ, 760, 120 “The 3.3 m Polycyclic A romatic H ydrocarbon E mission a s a S tar F ormation R ate I ndicator”8. Wang, J., et al. (Shi Y. 3rd author) 2011, MNRAS, 416, 21 “CS (5-­‐4) survey towards n earby i nfrared b right g alaxies”7. T yler, K. D., R ieke, G. H. e t a l. (Shi Y. 9th a uthor) 2011, A pJ, 738, 56 “The N ature of S tar F ormation a t 24 m i n t he G roup E nvironment a t 0.3 < z < 0.55”6. Wu, Y., et al. (Shi Y. 2nd author) 2011, ApJ, 734, 40 “The Mid-­‐infrared Luminosity Function at z < 0.3 from 5MUSES: Understanding the Star Formation/Active G alactic N ucleus B alance f rom a S pectroscopic V iew”5. W u, Y., e t a l. (Shi Y. 5th a uthor) 2010, A pJ, 723, 895 “Infrared L uminosities a nd Aromatic F eatures i n t he 24um F lux L imited S ample o f 5MUSES”4. Mason, R. E., et al. (Shi Y. 3nd author) 2009, ApJ, 693, 136 “The Origin of the Silicate E mission F eatures i n t he S eyfert 2 G alaxy N GC 2110”3. B allantyne, D. R., e t a l. (Shi Y. 2nd a uthor) 2006, A pJ, 653, 1070 “Does t he A GN Unified M odel E volve w ith R edshift? U sing t he X-­‐Ray B ackground t o P re-­‐ d ict t he Mid-­‐Infrared E mission o f A GNs”2. J iang, L. e t a l. (Shi Y. 4th a uthor) 2006, A J, 132, 2127 “Probing t he E volution o f Infrared P roperties o f z ∼6 Q uasars: S pitzer O bservations”1. Wu, Y. et al. (Shi Y. 4th author) 2004, A&A, 426, 503 “A study of high velocity molecular o utflows w ith a n u p-­‐to-­‐date s ample”。

天体英语知识点总结高中一、IntroductionThe study of celestial bodies, or heavenly bodies, is known as astronomy. Astronomy is a natural science that involves the observation and analysis of celestial phenomena. It has been a subject of human fascination for millennia, with civilizations around the world creating myths, legends, and astronomical calendars associated with the movements of the sun, moon, and stars.In recent centuries, astronomy has developed into a field of scientific inquiry, using advanced tools and techniques to study the universe and its contents. This has led to many groundbreaking discoveries and a better understanding of the cosmos.In this article, we will explore some key concepts and terms related to astronomy and celestial bodies, providing a comprehensive overview of this fascinating field of study.二、The Solar SystemThe solar system is the collection of celestial bodies that orbit the sun, including planets, moons, asteroids, comets, and other objects. The sun is the central star of the solar system, providing light and heat to the planets and other bodies that orbit it.1. Planets: There are eight recognized planets in the solar system, including Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. These planets vary in size, composition, and distance from the sun, and each has its own unique characteristics.2. Moons: Moons are natural satellites that orbit planets. The most well-known example is Earth's moon, but many other planets in the solar system also have moons of their own. Some planets, such as Jupiter and Saturn, have a large number of moons, while others have only a few.3. Asteroids: Asteroids are small, rocky bodies that orbit the sun. They are found primarily in the asteroid belt, which lies between the orbits of Mars and Jupiter. Some asteroids have elliptical or irregular orbits that bring them close to the inner solar system, posing a potential threat to Earth and other planets.4. Comets: Comets are icy bodies that orbit the sun in highly elliptical orbits. When a comet approaches the sun, its ice begins to vaporize, creating a bright glowing tail that can be seen from Earth. Comets are thought to be remnants from the early solar system and provide valuable insights into its formation and evolution.5. Dwarf Planets: In addition to the eight recognized planets, there are also a number of dwarf planets in the solar system. These are celestial bodies that are similar to planets in some ways but do not meet all the criteria for being classified as planets. The best-known example is Pluto, which was reclassified as a dwarf planet in 2006.三、Stars and GalaxiesStars are massive, luminous spheres of plasma that emit light and heat through nuclear fusion. They are the building blocks of galaxies, which are vast collections of stars, gas, and dust held together by gravity.1. Star Formation: Stars form from the gravitational collapse of dense regions within interstellar clouds of gas and dust. As the cloud contracts, it heats up and eventually reaches a temperature and density at which nuclear fusion reactions can occur, turning hydrogen into helium and releasing large amounts of energy in the process.2. Stellar Evolution: Stars go through a life cycle that depends on their initial mass. Low-mass stars, such as our sun, spend most of their lives in a stable state, fusing hydrogen into helium in their cores. Eventually, they exhaust their nuclear fuel and expand into red giants before shedding their outer layers and becoming white dwarfs. High-mass stars, on the other hand, undergo more dramatic evolutionary stages, including supernova explosions and the formation of neutron stars or black holes.3. Galaxies: Galaxies come in a variety of shapes and sizes, from small irregular galaxies to giant elliptical and spiral galaxies. The Milky Way, the galaxy in which our solar system resides, is a spiral galaxy with several arms of stars and gas. Galaxies are thought to have formed from the gravitational collapse of large clouds of gas and dust in the early universe.4. The Universe: The universe is the vast expanse of space and time that contains all known matter and energy. It is believed to have originated from a single point in an event known as the Big Bang, which occurred approximately 13.8 billion years ago. The study of the universe, its origin, and its evolution is a fundamental aspect of astronomy, leading to many important discoveries and insights into the nature of the cosmos.四、Observational AstronomyObservational astronomy is the study of celestial objects and phenomena through direct observation using telescopes, cameras, and other instruments. This branch of astronomy plays a crucial role in advancing our understanding of the universe.1. Telescopes: Telescopes are the primary tools used by astronomers to observe celestial objects. They collect and magnify light from distant objects, allowing astronomers to study stars, planets, galaxies, and other phenomena in great detail. There are several types of telescopes, including optical telescopes that work by collecting visible light, as well as radio telescopes, X-ray telescopes, and other specialized instruments that capture non-visible forms of radiation.2. Astronomical Imaging: Astronomical imaging refers to the process of capturing and analyzing images of celestial objects. Modern digital cameras and imaging sensors have revolutionized this field, allowing astronomers to produce high-resolution images of distantgalaxies, planetary surfaces, and other astronomical features. Imaging data is often used to study the composition, structure, and evolution of celestial bodies.3. Spectroscopy: Spectroscopy is the study of the interaction between light and matter. By analyzing the spectrum of light emitted or absorbed by an object, astronomers can learn about its composition, temperature, and other important properties. Spectroscopy has been instrumental in advancing our knowledge of stars, galaxies, and the interstellar medium.4. Astronomical Surveys: Astronomical surveys are large-scale projects that aim to systematically observe and catalog objects in the sky. These surveys cover a wide range of wavelengths and are used to study the distribution of galaxies, the structure of the universe, and the properties of individual celestial objects. The data collected from these surveys is crucial for advancing our understanding of the cosmos.五、Astrophysics and CosmologyAstrophysics is the branch of astronomy that seeks to understand the physical properties and behavior of celestial objects and phenomena. It involves the application of principles from physics and other sciences to study the universe and its contents.1. Stellar Physics: Stellar physics focuses on the study of stars, including their structure, evolution, and energy production. It seeks to explain the processes that govern the behavior of stars, such as nuclear fusion in their cores, the generation of magnetic fields, and the formation of stellar remnants.2. Galactic and Extragalactic Astrophysics: This subfield of astrophysics deals with the study of galaxies and the large-scale structures of the universe. It explores the distribution of matter and energy, the formation of galaxies, and the dynamics of galactic clusters. It also addresses the properties of objects outside our galaxy, such as quasars, pulsars, and active galactic nuclei.3. Cosmology: Cosmology is the study of the origin, evolution, and ultimate fate of the universe. It seeks to understand the large-scale structure of the cosmos, the nature of dark matter and dark energy, and the cosmic microwave background radiation left over from the Big Bang. Cosmologists use principles from general relativity and particle physics to develop theoretical models of the universe and test them against observational data.4. Black Holes and Neutron Stars: Black holes and neutron stars are extreme objects that result from the gravitational collapse of massive stars. They have unique properties, such as intense gravitational fields and the emission of powerful radiation. The study of these objects is an important area of research in astrophysics, as they provide insights into the behavior of matter under extreme conditions.六、ConclusionAstronomy is a fascinating and dynamic field of study that encompasses a wide range of topics, from the study of stars and planets to the exploration of the universe on the largest scales. It offers a unique perspective on the nature of our existence and our place in the cosmos.The knowledge and insights gained from astronomy have practical applications in many areas, including space exploration, the development of new technologies, and the search for extraterrestrial life. As our understanding of the universe continues to expand, so too will the impact of astronomy on our lives and our understanding of the world around us.In conclusion, astronomy is a cornerstone of human curiosity and scientific endeavor, revealing the wonders of the universe and the beauty of the celestial realm. The study of celestial bodies continues to capture the imagination of people around the world and drive us to explore and understand the cosmos in ever-greater detail.。

毕业设计（论文）题目：掺杂浓度对GaAs单量子阱中费米能级的影响学院：系部：专业：班级：学生姓名：导师姓名：职称：起止时间：毕业设计（论文）诚信声明书本人声明：本人所提交的毕业论文《掺杂浓度对GaAs单量子阱中费米能级的影响》是本人在指导教师指导下独立研究、写作的成果，论文中所引用他人的文献、数据、图件、资料均已明确标注；对本文的研究做出重要贡献的个人和集体，均已在文中以明确方式注明并表示感谢。

本人完全清楚本声明的法律后果，申请学位论文和资料若有不实之处，本人愿承担相应的法律责任。

论文作者签名：时间：年月日指导教师签名：时间：年月日目录摘要 (I)Abstract (II)1引言 (1)2砷化镓半导体量子阱 (2)2.1半导体材料简述 (2)2.2砷化镓半导体 (2)2.3低维半导体 (3)2.4费米能级 (3)2.5量子阱 (4)2.6砷化镓半导体的应用 (6)3量子阱相关的基本理论 (7)3.1量子力学与波函数 (7)3.2薛定谔方程 (8)3.2.1薛定谔波动方程的应用 (10)3.3有限差分法 (11)3.4求解本征能级能量 (12)3.5求解费米能级 (14)4掺杂浓度对费米能级的影响 (16)4.1量子阱结构 (16)4.2软件计算 (16)4.3数值结果 (17)4.4数值分析 (19)5结论 (20)致谢 (21)参考文献 (22)附录 (23)摘要单量子阱可以按照自己的意愿对半导体化合物分组和生长厚度进行控制，在不同的量子阱中电子的运动也会发生变化，电子的运动状态会影响到量子阱的能级能量。

费米能级存在于两相邻能级之间，它的位置可以决定载流子分布状态。

载流子的浓度会影响半导体的物理性能，从而可以制作出各种各样的半导体器件。

然而，费米能级的位置不是一个固定不变的值，它会随着外界施主杂质掺杂浓度和温度的变化而变化。

首先，本文会介绍半导体物理的知识，系统的介绍量子阱方面的内容，然后再引出砷化镓半导体。

黑洞的由来的英语作文The Origin of Black Holes: A Journey into Cosmic Mysteries。

Introduction。

Black holes, enigmatic entities lurking in the depthsof space, have captivated the imagination of scientists and laypersons alike. Their origins, shrouded in cosmic mystery, have been the subject of intense study and speculation. In this essay, we embark on a journey to unravel the secretsof black holes, exploring their formation, properties, and significance in the universe.Formation of Black Holes。

The genesis of black holes begins with the demise of massive stars. When a massive star exhausts its nuclear fuel, it undergoes a cataclysmic event known as a supernova explosion. During this explosive phase, the outer layers ofthe star are ejected into space, while its core undergoes gravitational collapse. If the core's mass exceeds acritical threshold, it collapses into a singularity—a point of infinite density—giving birth to a black hole.The process of black hole formation can also occur through the gravitational collapse of dense stellar remnants, such as neutron stars, or through the merger of two compact objects, such as neutron stars or black holes. These pathways lead to the creation of different types of black holes, ranging from stellar-mass black holes to supermassive black holes found at the centers of galaxies.Properties of Black Holes。

科普知识英语作文八百字The Enigmatic World of Black Holes: Exploring the Cosmic Colossi.In the vast and uncharted expanses of our universe reside enigmatic celestial entities that captivate the imaginations of astrophysicists and laypeople alike: black holes. These enigmatic cosmic giants, characterized bytheir immense gravitational pull and enigmatic nature, have long been a subject of scientific fascination and speculation.Birth and Formation.The genesis of a black hole is a cataclysmic event the gravitational collapse of a massive star. When a star exhausts its nuclear fuel, its core undergoes a gravitational implosion, resulting in an immense explosion known as a supernova. If the star's mass surpasses acritical threshold, known as the Chandrasekhar limit, thesupernova remnants collapse further under their own gravity, forming a singularity a point of infinite density and zero volume. This singularity is encased within an invisible boundary called an event horizon, beyond which light itself cannot escape the gravitational pull.Size and Mass.Black holes vary greatly in size and mass. Stellar-mass black holes, formed from the collapse of individual stars, typically possess masses ranging from several to tens of solar masses. Supermassive black holes, on the other hand, are colossal entities residing at the heart of most galaxies, with masses that can exceed billions of solar masses.Gravitational Pull.The most defining characteristic of black holes istheir immense gravitational pull. The gravitational field within the event horizon is so intense that nothing, not even light, can escape its clutches. Matter and energy thatventure too close are inexorably drawn into the singularity, where they are crushed and compressed to unthinkable densities.Singularity and Hawking Radiation.At the center of a black hole lies the singularity, a region of infinite density and zero volume. It represents the ultimate point of gravitational collapse, and its properties defy our current understanding of physics. In 1974, renowned physicist Stephen Hawking proposed the concept of Hawking radiation, suggesting that quantumeffects allow black holes to emit faint radiation due tothe gravitational interactions at their event horizons.Event Horizon.The event horizon, a boundary around the black hole, marks the point of no return. Once matter crosses the event horizon, it is irrevocably trapped within the black hole's gravitational grasp, forever lost to the outside universe. The event horizon itself is a theoretical surface that isinvisible to observers, but its presence can be inferred from gravitational effects on surrounding matter.Accretion Disks and Jet Streams.As matter falls towards a black hole, it forms a swirling disk of gas and dust called an accretion disk. This disk emits intense radiation as the infalling matter is heated and compressed. Some black holes also exhibit powerful jets of matter that are expelled from their poles at near-light speeds. These jets are thought to be generated by the magnetic fields that permeate the black hole's environment.Role in Galaxies.Supermassive black holes are believed to play a crucial role in the formation and evolution of galaxies. Their gravitational influence shapes the distribution of stars and gas within galaxies, and they may act as engines for the activity observed in galactic nuclei. By studying the properties and behavior of black holes in galaxies,astrophysicists can gain insights into the fundamental processes that govern the universe.Observing Black Holes.Directly observing black holes is impossible due to their inherent darkness and the inability of light to escape their event horizons. However, scientists can study them indirectly by observing their effects on surrounding matter. By analyzing the motion of stars and gas near black holes, astronomers can infer their presence and estimate their masses. The first direct image of a black hole, known as M87, was captured in 2019 by the Event Horizon Telescope (EHT), an international collaboration of radio telescopes.Conclusion.Black holes remain enigmatic cosmic entities that continue to captivate and intrigue scientists and laypeople alike. Their immense gravitational pull, enigmatic nature, and potential role in shaping the universe make them fascinating subjects of ongoing research. As ourunderstanding of black holes deepens, we may unlock further insights into the fundamental laws that govern our universe and the enigmatic nature of space and time.。

关于太空现象的英语术语Space Exploration and Its TerminologySpace exploration has been a captivating field of study for centuries, capturing the imaginations of people around the world. As we delve deeper into the mysteries of the cosmos, the need for precise and comprehensive terminology becomes increasingly important. This essay will explore some of the key terms and concepts associated with space phenomena, providing a comprehensive overview of the language used in this fascinating domain.One of the most fundamental terms in space exploration is "galaxy."A galaxy is a vast, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter. Our own Milky Way galaxy is just one of the countless galaxies that populate the observable universe, each with its own unique characteristics and composition. The study of galaxies, their formation, evolution, and interactions, is a crucial aspect of astrophysics.Another essential term in the realm of space is "star." Stars are massive, luminous celestial bodies held together by their own gravity. They are the building blocks of galaxies and play a crucial role in thelife cycle of the universe. The study of stars, their properties, and their life cycles is known as stellar astronomy or stellar astrophysics.Closely related to stars are the concept of "exoplanets." Exoplanets are planets that orbit stars other than our Sun. The discovery and study of exoplanets have revolutionized our understanding of planetary systems and the potential for life beyond Earth. Astronomers use various techniques, such as the transit method and the radial velocity method, to detect and characterize these distant worlds.Another important term in space exploration is "nebula." A nebula is a vast, diffuse cloud of gas and dust in space, often illuminated by the light of nearby stars or energized by the radiation from young, hot stars. Nebulae play a crucial role in the formation of stars and can take on a variety of shapes and colors, depending on their composition and the processes occurring within them.The concept of "black holes" is also central to our understanding of space phenomena. Black holes are regions in space where the gravitational pull is so strong that nothing, not even light, can escape. These enigmatic objects are formed when a massive star collapses in on itself, and their study has led to groundbreaking discoveries in the field of general relativity and the nature of spacetime.In addition to these fundamental terms, space exploration also encompasses a wide range of specialized vocabulary. For example, "supernova" refers to the explosive death of a massive star, while "neutron star" describes the extremely dense, rapidly rotating remnant of a supernova. "Quasar" is a term used to describe the extremely luminous and energetic cores of active galactic nuclei, powered by supermassive black holes.The language of space exploration also includes terms related to the various instruments and technologies used to study the cosmos. "Telescope" is a device that uses lenses or mirrors to gather and focus light, allowing astronomers to observe distant celestial objects in detail. "Spectrometer" is an instrument that analyzes the spectrum of light emitted or absorbed by an object, providing valuable information about its composition and physical properties.Finally, the field of space exploration is also closely tied to the concept of "cosmology," the study of the origin, evolution, and ultimate fate of the universe. Fundamental terms in cosmology include "Big Bang," the proposed initial state of the universe, and "dark matter" and "dark energy," the mysterious components that make up the majority of the universe's mass and energy.In conclusion, the language of space exploration is rich and diverse, reflecting the depth and complexity of our understanding of thecosmos. From the basic terms like "galaxy" and "star" to the more specialized concepts like "exoplanet" and "quasar," the vocabulary of this field is essential for scientists, researchers, and enthusiasts alike to communicate and share their discoveries. As we continue to explore the wonders of the universe, the importance of this specialized terminology will only grow, serving as a crucial tool for expanding our knowledge and understanding of the cosmos.。

Lindqvist 钨酸盐形成机理的理论研究Lindqvist 钨酸盐形成机理的理论研究#郎中玲，关威，温世正，颜力楷，苏忠民**（东北师范大学化学学院功能材料所，长春 130024）10 15 20 25 30 35 40摘要：多酸化合物的形成机理是一直是多酸化学的基础性问题。

本文采用密度泛函方法对Lindqvist 型 [W6O19]2-阴离子在水溶液中形成过程进行研究。

研究表明，两种机理从热力学和动力学上都是允许的，且机理 2 比机理 1 略占优势。

两种机理中五核中间体[W5O16]2- 和[W5O15 OH ]-的形成是反应中的决速步骤，分别克服 30.48 和 28.90 kcal/mol 能垒。

[W4O13]2-和 [W4O12 OH ]-被证明是反应中的最稳定的构筑单元。

理论计算还表明对于[W3O10]2-的形成主要是按照链型的路径进行。

关键词：多金属氧酸盐；钨酸盐；形成机理；自组装；热力学；密度泛函理论计算中图分类号：O642.1The Self-Assembly Mechanism of Lindqvist Anion [W6O19]2-in Aqueous: A Density Functional Theory StudyLANG Zhongling, GUAN Wei, WEN Shizheng, YAN Likai, SU ZhongminInstitute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University,ChangChun 130024Abstract: The formation mechanism is always a fundamental and confused issue forpolyoxometalate chemistry. Two formation mechanisms M1 and M2 of Lindqvist anion[W6O19]2- have been adopted to investigate it’s self-assembly reaction pathways at densityfunctional theory DFT level. Potential energy surfaces reveal that both the two mechanisms arethermodynamically favorable and overall barrierless at room temperature, but M2 is slightlydominant than M1. The formation of pentanuclear species [W5O16]2- and [W5O15 OH ]- isrecognized as the rate-determining steps in the whole assembly polymerization processes. Thesetwo steps involve the highest energy barriers with 30.48 kcal/mol and 28.90 kcal/mol, respectivelyfor M1 and M2. [W4O13]2- and [W4O12 OH ]- are proved to be the most stable building blocks.In addition, DFT results reveal that formation of [W3O10]2- experiences a lower barriers along thechain channel.Keywords: Polyoxometalates; Phosphotungstic acid; Formation mechanism; Self-assembly;Thermodynamic; Density functional theory calculations0 引言多酸化合物是金属氧化物中一类庞大的分子团簇，表现出各种优越的物理化学性质并广泛应用到催化，医学，磁学，光学和传导等方面[1-18]。

华中师范大学物理学院物理学专业英语仅供内部学习参考！2014一、课程的任务和教学目的通过学习《物理学专业英语》，学生将掌握物理学领域使用频率较高的专业词汇和表达方法，进而具备基本的阅读理解物理学专业文献的能力。

通过分析《物理学专业英语》课程教材中的范文，学生还将从英语角度理解物理学中个学科的研究内容和主要思想，提高学生的专业英语能力和了解物理学研究前沿的能力。

培养专业英语阅读能力，了解科技英语的特点，提高专业外语的阅读质量和阅读速度；掌握一定量的本专业英文词汇，基本达到能够独立完成一般性本专业外文资料的阅读；达到一定的笔译水平。

要求译文通顺、准确和专业化。

要求译文通顺、准确和专业化。

二、课程内容课程内容包括以下章节：物理学、经典力学、热力学、电磁学、光学、原子物理、统计力学、量子力学和狭义相对论三、基本要求1.充分利用课内时间保证充足的阅读量（约1200~1500词/学时），要求正确理解原文。

2.泛读适量课外相关英文读物，要求基本理解原文主要内容。

3.掌握基本专业词汇（不少于200词）。

4.应具有流利阅读、翻译及赏析专业英语文献，并能简单地进行写作的能力。

四、参考书目录1 Physics 物理学 (1)Introduction to physics (1)Classical and modern physics (2)Research fields (4)V ocabulary (7)2 Classical mechanics 经典力学 (10)Introduction (10)Description of classical mechanics (10)Momentum and collisions (14)Angular momentum (15)V ocabulary (16)3 Thermodynamics 热力学 (18)Introduction (18)Laws of thermodynamics (21)System models (22)Thermodynamic processes (27)Scope of thermodynamics (29)V ocabulary (30)4 Electromagnetism 电磁学 (33)Introduction (33)Electrostatics (33)Magnetostatics (35)Electromagnetic induction (40)V ocabulary (43)5 Optics 光学 (45)Introduction (45)Geometrical optics (45)Physical optics (47)Polarization (50)V ocabulary (51)6 Atomic physics 原子物理 (52)Introduction (52)Electronic configuration (52)Excitation and ionization (56)V ocabulary (59)7 Statistical mechanics 统计力学 (60)Overview (60)Fundamentals (60)Statistical ensembles (63)V ocabulary (65)8 Quantum mechanics 量子力学 (67)Introduction (67)Mathematical formulations (68)Quantization (71)Wave-particle duality (72)Quantum entanglement (75)V ocabulary (77)9 Special relativity 狭义相对论 (79)Introduction (79)Relativity of simultaneity (80)Lorentz transformations (80)Time dilation and length contraction (81)Mass-energy equivalence (82)Relativistic energy-momentum relation (86)V ocabulary (89)正文标记说明：蓝色Arial字体（例如energy）：已知的专业词汇蓝色Arial字体加下划线（例如electromagnetism）：新学的专业词汇黑色Times New Roman字体加下划线（例如postulate）：新学的普通词汇1 Physics 物理学1 Physics 物理学Introduction to physicsPhysics is a part of natural philosophy and a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the Scientific Revolution in the 17th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry,and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy.Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.Core theoriesThough physics deals with a wide variety of systems, certain theories are used by all physicists. Each of these theories were experimentally tested numerous times and found correct as an approximation of nature (within a certain domain of validity).For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These theories continue to be areas of active research, and a remarkable aspect of classical mechanics known as chaos was discovered in the 20th century, three centuries after the original formulation of classical mechanics by Isaac Newton (1642–1727) 【艾萨克·牛顿】.University PhysicsThese central theories are important tools for research into more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them. These include classical mechanics, quantum mechanics, thermodynamics and statistical mechanics, electromagnetism, and special relativity.Classical and modern physicsClassical mechanicsClassical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism.Classical mechanics is concerned with bodies acted on by forces and bodies in motion and may be divided into statics (study of the forces on a body or bodies at rest), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanics and fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, and pneumatics.Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics include ultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics.Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light.Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy.Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at rest.Modern PhysicsClassical physics is generally concerned with matter and energy on the normal scale of1 Physics 物理学observation, while much of modern physics is concerned with the behavior of matter and energy under extreme conditions or on the very large or very small scale.For example, atomic and nuclear physics studies matter on the smallest scale at which chemical elements can be identified.The physics of elementary particles is on an even smaller scale, as it is concerned with the most basic units of matter; this branch of physics is also known as high-energy physics because of the extremely high energies necessary to produce many types of particles in large particle accelerators. On this scale, ordinary, commonsense notions of space, time, matter, and energy are no longer valid.The two chief theories of modern physics present a different picture of the concepts of space, time, and matter from that presented by classical physics.Quantum theory is concerned with the discrete, rather than continuous, nature of many phenomena at the atomic and subatomic level, and with the complementary aspects of particles and waves in the description of such phenomena.The theory of relativity is concerned with the description of phenomena that take place in a frame of reference that is in motion with respect to an observer; the special theory of relativity is concerned with relative uniform motion in a straight line and the general theory of relativity with accelerated motion and its connection with gravitation.Both quantum theory and the theory of relativity find applications in all areas of modern physics.Difference between classical and modern physicsWhile physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions.Albert Einstein【阿尔伯特·爱因斯坦】contributed the framework of special relativity, which replaced notions of absolute time and space with space-time and allowed an accurate description of systems whose components have speeds approaching the speed of light.Max Planck【普朗克】, Erwin Schrödinger【薛定谔】, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales.Later, quantum field theory unified quantum mechanics and special relativity.General relativity allowed for a dynamical, curved space-time, with which highly massiveUniversity Physicssystems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed.Research fieldsContemporary research in physics can be broadly divided into condensed matter physics; atomic, molecular, and optical physics; particle physics; astrophysics; geophysics and biophysics. Some physics departments also support research in Physics education.Since the 20th century, the individual fields of physics have become increasingly specialized, and today most physicists work in a single field for their entire careers. "Universalists" such as Albert Einstein (1879–1955) and Lev Landau (1908–1968)【列夫·朗道】, who worked in multiple fields of physics, are now very rare.Condensed matter physicsCondensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of particles in a system is extremely large and the interactions between them are strong.The most familiar examples of condensed phases are solids and liquids, which arise from the bonding by way of the electromagnetic force between atoms. More exotic condensed phases include the super-fluid and the Bose–Einstein condensate found in certain atomic systems at very low temperature, the superconducting phase exhibited by conduction electrons in certain materials,and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices.Condensed matter physics is by far the largest field of contemporary physics.Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term condensed matter physics was apparently coined by Philip Anderson when he renamed his research group—previously solid-state theory—in 1967. In 1978, the Division of Solid State Physics of the American Physical Society was renamed as the Division of Condensed Matter Physics.Condensed matter physics has a large overlap with chemistry, materials science, nanotechnology and engineering.Atomic, molecular and optical physicsAtomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions on the scale of single atoms and molecules.1 Physics 物理学The three areas are grouped together because of their interrelationships, the similarity of methods used, and the commonality of the energy scales that are relevant. All three areas include both classical, semi-classical and quantum treatments; they can treat their subject from a microscopic view (in contrast to a macroscopic view).Atomic physics studies the electron shells of atoms. Current research focuses on activities in quantum control, cooling and trapping of atoms and ions, low-temperature collision dynamics and the effects of electron correlation on structure and dynamics. Atomic physics is influenced by the nucleus (see, e.g., hyperfine splitting), but intra-nuclear phenomena such as fission and fusion are considered part of high-energy physics.Molecular physics focuses on multi-atomic structures and their internal and external interactions with matter and light.Optical physics is distinct from optics in that it tends to focus not on the control of classical light fields by macroscopic objects, but on the fundamental properties of optical fields and their interactions with matter in the microscopic realm.High-energy physics (particle physics) and nuclear physicsParticle physics is the study of the elementary constituents of matter and energy, and the interactions between them.In addition, particle physicists design and develop the high energy accelerators,detectors, and computer programs necessary for this research. The field is also called "high-energy physics" because many elementary particles do not occur naturally, but are created only during high-energy collisions of other particles.Currently, the interactions of elementary particles and fields are described by the Standard Model.●The model accounts for the 12 known particles of matter (quarks and leptons) thatinteract via the strong, weak, and electromagnetic fundamental forces.●Dynamics are described in terms of matter particles exchanging gauge bosons (gluons,W and Z bosons, and photons, respectively).●The Standard Model also predicts a particle known as the Higgs boson. In July 2012CERN, the European laboratory for particle physics, announced the detection of a particle consistent with the Higgs boson.Nuclear Physics is the field of physics that studies the constituents and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those in nuclear medicine and magnetic resonance imaging, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology.University PhysicsAstrophysics and Physical CosmologyAstrophysics and astronomy are the application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.The discovery by Karl Jansky in 1931 that radio signals were emitted by celestial bodies initiated the science of radio astronomy. Most recently, the frontiers of astronomy have been expanded by space exploration. Perturbations and interference from the earth's atmosphere make space-based observations necessary for infrared, ultraviolet, gamma-ray, and X-ray astronomy.Physical cosmology is the study of the formation and evolution of the universe on its largest scales. Albert Einstein's theory of relativity plays a central role in all modern cosmological theories. In the early 20th century, Hubble's discovery that the universe was expanding, as shown by the Hubble diagram, prompted rival explanations known as the steady state universe and the Big Bang.The Big Bang was confirmed by the success of Big Bang nucleo-synthesis and the discovery of the cosmic microwave background in 1964. The Big Bang model rests on two theoretical pillars: Albert Einstein's general relativity and the cosmological principle (On a sufficiently large scale, the properties of the Universe are the same for all observers). Cosmologists have recently established the ΛCDM model (the standard model of Big Bang cosmology) of the evolution of the universe, which includes cosmic inflation, dark energy and dark matter.Current research frontiersIn condensed matter physics, an important unsolved theoretical problem is that of high-temperature superconductivity. Many condensed matter experiments are aiming to fabricate workable spintronics and quantum computers.In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appear. Foremost among these are indications that neutrinos have non-zero mass. These experimental results appear to have solved the long-standing solar neutrino problem, and the physics of massive neutrinos remains an area of active theoretical and experimental research. Particle accelerators have begun probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the super-symmetric particles, after discovery of the Higgs boson.Theoretical attempts to unify quantum mechanics and general relativity into a single theory1 Physics 物理学of quantum gravity, a program ongoing for over half a century, have not yet been decisively resolved. The current leading candidates are M-theory, superstring theory and loop quantum gravity.Many astronomical and cosmological phenomena have yet to be satisfactorily explained, including the existence of ultra-high energy cosmic rays, the baryon asymmetry, the acceleration of the universe and the anomalous rotation rates of galaxies.Although much progress has been made in high-energy, quantum, and astronomical physics, many everyday phenomena involving complexity, chaos, or turbulence are still poorly understood. Complex problems that seem like they could be solved by a clever application of dynamics and mechanics remain unsolved; examples include the formation of sand-piles, nodes in trickling water, the shape of water droplets, mechanisms of surface tension catastrophes, and self-sorting in shaken heterogeneous collections.These complex phenomena have received growing attention since the 1970s for several reasons, including the availability of modern mathematical methods and computers, which enabled complex systems to be modeled in new ways. Complex physics has become part of increasingly interdisciplinary research, as exemplified by the study of turbulence in aerodynamics and the observation of pattern formation in biological systems.Vocabulary★natural science 自然科学academic disciplines 学科astronomy 天文学in their own right 凭他们本身的实力intersects相交，交叉interdisciplinary交叉学科的，跨学科的★quantum 量子的theoretical breakthroughs 理论突破★electromagnetism 电磁学dramatically显著地★thermodynamics热力学★calculus微积分validity★classical mechanics 经典力学chaos 混沌literate 学者★quantum mechanics量子力学★thermodynamics and statistical mechanics热力学与统计物理★special relativity狭义相对论is concerned with 关注，讨论，考虑acoustics 声学★optics 光学statics静力学at rest 静息kinematics运动学★dynamics动力学ultrasonics超声学manipulation 操作，处理，使用University Physicsinfrared红外ultraviolet紫外radiation辐射reflection 反射refraction 折射★interference 干涉★diffraction 衍射dispersion散射★polarization 极化，偏振internal energy 内能Electricity电性Magnetism 磁性intimate 亲密的induces 诱导，感应scale尺度★elementary particles基本粒子★high-energy physics 高能物理particle accelerators 粒子加速器valid 有效的，正当的★discrete离散的continuous 连续的complementary 互补的★frame of reference 参照系★the special theory of relativity 狭义相对论★general theory of relativity 广义相对论gravitation 重力，万有引力explicit 详细的，清楚的★quantum field theory 量子场论★condensed matter physics凝聚态物理astrophysics天体物理geophysics地球物理Universalist博学多才者★Macroscopic宏观Exotic奇异的★Superconducting 超导Ferromagnetic铁磁质Antiferromagnetic 反铁磁质★Spin自旋Lattice 晶格，点阵，网格★Society社会，学会★microscopic微观的hyperfine splitting超精细分裂fission分裂，裂变fusion熔合，聚变constituents成分，组分accelerators加速器detectors 检测器★quarks夸克lepton 轻子gauge bosons规范玻色子gluons胶子★Higgs boson希格斯玻色子CERN欧洲核子研究中心★Magnetic Resonance Imaging磁共振成像，核磁共振ion implantation 离子注入radiocarbon dating放射性碳年代测定法geology地质学archaeology考古学stellar 恒星cosmology宇宙论celestial bodies 天体Hubble diagram 哈勃图Rival竞争的★Big Bang大爆炸nucleo-synthesis核聚合，核合成pillar支柱cosmological principle宇宙学原理ΛCDM modelΛ-冷暗物质模型cosmic inflation宇宙膨胀1 Physics 物理学fabricate制造，建造spintronics自旋电子元件，自旋电子学★neutrinos 中微子superstring 超弦baryon重子turbulence湍流，扰动，骚动catastrophes突变，灾变，灾难heterogeneous collections异质性集合pattern formation模式形成University Physics2 Classical mechanics 经典力学IntroductionIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology.Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. Besides this, many specializations within the subject deal with gases, liquids, solids, and other specific sub-topics.Classical mechanics provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light. When the objects being dealt with become sufficiently small, it becomes necessary to introduce the other major sub-field of mechanics, quantum mechanics, which reconciles the macroscopic laws of physics with the atomic nature of matter and handles the wave–particle duality of atoms and molecules. In the case of high velocity objects approaching the speed of light, classical mechanics is enhanced by special relativity. General relativity unifies special relativity with Newton's law of universal gravitation, allowing physicists to handle gravitation at a deeper level.The initial stage in the development of classical mechanics is often referred to as Newtonian mechanics, and is associated with the physical concepts employed by and the mathematical methods invented by Newton himself, in parallel with Leibniz【莱布尼兹】, and others.Later, more abstract and general methods were developed, leading to reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advances were largely made in the 18th and 19th centuries, and they extend substantially beyond Newton's work, particularly through their use of analytical mechanics. Ultimately, the mathematics developed for these were central to the creation of quantum mechanics.Description of classical mechanicsThe following introduces the basic concepts of classical mechanics. For simplicity, it often2 Classical mechanics 经典力学models real-world objects as point particles, objects with negligible size. The motion of a point particle is characterized by a small number of parameters: its position, mass, and the forces applied to it.In reality, the kind of objects that classical mechanics can describe always have a non-zero size. (The physics of very small particles, such as the electron, is more accurately described by quantum mechanics). Objects with non-zero size have more complicated behavior than hypothetical point particles, because of the additional degrees of freedom—for example, a baseball can spin while it is moving. However, the results for point particles can be used to study such objects by treating them as composite objects, made up of a large number of interacting point particles. The center of mass of a composite object behaves like a point particle.Classical mechanics uses common-sense notions of how matter and forces exist and interact. It assumes that matter and energy have definite, knowable attributes such as where an object is in space and its speed. It also assumes that objects may be directly influenced only by their immediate surroundings, known as the principle of locality.In quantum mechanics objects may have unknowable position or velocity, or instantaneously interact with other objects at a distance.Position and its derivativesThe position of a point particle is defined with respect to an arbitrary fixed reference point, O, in space, usually accompanied by a coordinate system, with the reference point located at the origin of the coordinate system. It is defined as the vector r from O to the particle.In general, the point particle need not be stationary relative to O, so r is a function of t, the time elapsed since an arbitrary initial time.In pre-Einstein relativity (known as Galilean relativity), time is considered an absolute, i.e., the time interval between any given pair of events is the same for all observers. In addition to relying on absolute time, classical mechanics assumes Euclidean geometry for the structure of space.Velocity and speedThe velocity, or the rate of change of position with time, is defined as the derivative of the position with respect to time. In classical mechanics, velocities are directly additive and subtractive as vector quantities; they must be dealt with using vector analysis.When both objects are moving in the same direction, the difference can be given in terms of speed only by ignoring direction.University PhysicsAccelerationThe acceleration , or rate of change of velocity, is the derivative of the velocity with respect to time (the second derivative of the position with respect to time).Acceleration can arise from a change with time of the magnitude of the velocity or of the direction of the velocity or both . If only the magnitude v of the velocity decreases, this is sometimes referred to as deceleration , but generally any change in the velocity with time, including deceleration, is simply referred to as acceleration.Inertial frames of referenceWhile the position and velocity and acceleration of a particle can be referred to any observer in any state of motion, classical mechanics assumes the existence of a special family of reference frames in terms of which the mechanical laws of nature take a comparatively simple form. These special reference frames are called inertial frames .An inertial frame is such that when an object without any force interactions (an idealized situation) is viewed from it, it appears either to be at rest or in a state of uniform motion in a straight line. This is the fundamental definition of an inertial frame. They are characterized by the requirement that all forces entering the observer's physical laws originate in identifiable sources (charges, gravitational bodies, and so forth).A non-inertial reference frame is one accelerating with respect to an inertial one, and in such a non-inertial frame a particle is subject to acceleration by fictitious forces that enter the equations of motion solely as a result of its accelerated motion, and do not originate in identifiable sources. These fictitious forces are in addition to the real forces recognized in an inertial frame.A key concept of inertial frames is the method for identifying them. For practical purposes, reference frames that are un-accelerated with respect to the distant stars are regarded as good approximations to inertial frames.Forces; Newton's second lawNewton was the first to mathematically express the relationship between force and momentum . Some physicists interpret Newton's second law of motion as a definition of force and mass, while others consider it a fundamental postulate, a law of nature. Either interpretation has the same mathematical consequences, historically known as "Newton's Second Law":a m t v m t p F ===d )(d d dThe quantity m v is called the (canonical ) momentum . The net force on a particle is thus equal to rate of change of momentum of the particle with time.So long as the force acting on a particle is known, Newton's second law is sufficient to。