ImageVerifierCode 换一换
格式:PDF , 页数:58 ,大小:463.90KB ,
资源ID:75496      下载积分:8 积分
快捷下载
登录下载
邮箱/手机:
温馨提示:
快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。 如填写123,账号就是123,密码也是123。
特别说明:
请自助下载,系统不会自动发送文件的哦; 如果您已付费,想二次下载,请登录后访问:我的下载记录
支付方式: 支付宝扫码支付 微信扫码支付   
验证码:   换一换

加入VIP,免费下载
 

温馨提示:由于个人手机设置不同,如果发现不能下载,请复制以下地址【https://www.wnwk.com/docdown/75496.html】到电脑端继续下载(重复下载不扣费)。

已注册用户请登录:
账号:
密码:
验证码:   换一换
  忘记密码?
三方登录: QQ登录  

下载须知

1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。
2: 试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。
3: 文件的所有权益归上传用户所有。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 本站仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

版权提示 | 免责声明

本文(复旦大学《大学物理》课件(英文)-第20章 The special theory of (1).pdf)为本站会员(嘭**)主动上传,蜗牛文库仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知蜗牛文库(发送邮件至admin@wnwk.com或直接QQ联系客服),我们立即给予删除!

复旦大学《大学物理》课件(英文)-第20章 The special theory of (1).pdf

1、Chapter 20 The special theory of relativityAlbert Einstein (1879 1955)20-1 Troubles with classical physicsThe kinematics developed by Galileo and the mechanics developed by Newton,which form the basis of what we call“classical physics”,had many triumphs.However,a number of experimental phenomena can

2、 not be understoodwith these otherwise successful classical theories.1.Troubles with our ideas about timeThe pions(or )created at rest are observed+to decay(to other particles)with an average lifetime of only .In one particular experiment,pions were created in motion at a speed of.In this case they

3、were observed to travel in the laboratory an average distance of before decaying,from which we conclude that they decay in a time given by,much larger than the lifetime measured for pions at rest.This effect,called“time dilation”,which cannot be explained by Newtonian physics.In Newtonian physics ti

4、me is a universal coordinate having identical values for all observers.ns0.26cv913.0=nsvD7.63=mD4.17=2.Trouble with our ideas about lengthSuppose an observer in the above laboratory placed one marker at the location of the pions formation and another at the location of its decay.The distance between

5、 the markers is measured to be 17.4m.Now consider the observer who is traveling along with the pion at a speed of u=0.913c.This observer,to whom the pion appear to be at rest,measures its lifetime to be 26.0ns,and the distance between the markers is Thus two observers measure different value for the

6、 same length interval.mc1.7)100.26)(913.0(9=3.Troubles with our ideas about light20-2 The postulates of special relativity1.Einstein offered two postulates that form the basis of his special theory of relativity.(I)The principle of relativity:“The laws of physics are the same in all inertial referen

7、ce frames.”(II)The principle of the constancy of the speed oflight:“The speed of light in free space has the same value c in all inertial reference frames.”2.The first postulate declares that the laws of physics are absolute,universal,and same for all inertial observers.The Second postulate is much

8、more difficult to accept,because it violates our“common sense”,which is firmly grounded in the Galilean kinematics that we have learned from everyday experiences.It implies that“it is impossible to accelerate a particle to a speed greater than c”.20-3 Consequences of Einsteins postulates1.The relati

9、vity of timeWe consider two observers:S is at rest on the ground,and S is in a train moving on a long straight track at constant speed u relative to S.The observers carry identical timing devices,illustrated in Fig 20-4,consisting of a flashing light bulb F attached to a detector D and separated by

10、a distance from a mirror M.The bulb emits a flash of light that travels to the mirror,when the reflected light returns to D,the clock ticks and another flash is triggered.0LThe time interval between ticks is:(20-1)The interval is observed by either S or S when the clock is at rest respect to that ob

11、server.MFDFig 20-40L0tcLt002=0tWe now consider the situation when one observer looks at a clock carried by the other.Fig 20-5 shows that S observes on the clock carried by S on the moving train.F DSABCLLSSStuFig 20-5FFDDAccording to S,the flash is emitted at A,reflected at B,and detected at C.This i

12、nterval is(20-20)Substituting for from Eq(20-1)and solving Eq(20-2)for gives(20-3)ctuLcLt220)2(22+=20)(1cutt=tt0LThe time interval measured by the observer(S)relative to whom the clock is at rest is called the“proper time(正确时间)”,and .That is,the observer relative to whom the clock is in motion measu

13、res a greater interval between ticks.This effect is called“time dilation”.All observer in motion relative to the clock measure“longer intervals”.0ttt0Eq(20-3)is valid for any direction of the relative motion of S and S.2.The relativity of lengthFig 20-6 shows the sequence of events as observed by S

14、for the moving clock which is on the train sideway,so that the light now travels along the direction of motion of the train.According to S the length of the clock is L,which is different from the length measured by S,relative to whom the clock is at rest.0L(A)(B)LS(C)SSSuu1tu2tu2tc22tuLtc=11tctuL=+F

15、ig 20-6uMFD0LFDFDFDIn the process from A,B to C,the total time taken is(20-6)From Eq(20-3),setting(20-7)Setting Eqs(20-6)and(20-7)equal to one another and solving,we obtain(20-8)221)(112cucLucLucLttt=+=+=2020)(112)(1cucLcutt=cLt002=20)(1cuLL=Eq(20-8)summarizes the effect known as“length contraction”

16、.(a)The lengthmeasured by an observer who is at rest with respect to the object being measured is called the“rest length”or“proper length”.(b)All observers in motion relative to S measure a shorter length,but only for dimensions along the direction of motion;length measurement transverse to the direction of motion are unaffected.0L(c)Under ordinary circumstances,and the effects of length contraction are too small to be observed.cu3 The relativistic addition of velocities Let us now modify our ti

copyright@ 2008-2023 wnwk.com网站版权所有

经营许可证编号:浙ICP备2024059924号-2