问题 多选题

如图所示,物体A、B通过细绳及轻质弹簧连接在轻滑轮两侧,物体A、B的质量分别为m、2m,开始时细绳伸直,用手托着物体A使弹簧处于原长,且物体A与地面的距离为h,物体B静止在地面上.放手后物体A下落,与地面即将接触时速度为v,此时物体B对地面恰好无压力.若在物体A下落的过程中弹簧始终处于弹性限度内,则下列说法不正确的是(  )

A.下落过程中物体A的机械能守恒

B.整个过程中物体A重力势能的减小量等于弹簧的弹性势能增加量

C.弹簧的最大弹性势能等于mgh-

1
2
mv2

D.弹簧对物体A拉力的瞬时功率大小为2mgv

答案

A、下落过程中物体A与弹簧系统机械能守恒,而物体A的机械能有一部分转化为弹簧的势能,一部分转化为动能,所以物体A机械能不守恒,A错误.

B、物体A在下落到地面过程中,重力势能减小,动能增加,弹性势能增加,则A重力势能的减小量大于弹簧弹性势能的增加量.故B错误.

C、根据能量守恒定律知:mgh=EP+

1
2
mv2,故C正确;

D、接触在面瞬间,弹簧的弹力等于物体B的重力,所以弹力对物体A做功功率P=mgυ,故D正确.

本题选错误的,故选AB.

阅读理解

Tailors English Language Preparation 2010

Taylorscollege. edu. au/ telp

If you need additional help to gain the high level of English language necessary for academic study, Taylors English Language Preparation (TELP)is the perfect solution. Throughout your TELP studies you will be an active language learner. You will be surrounded by opportunities to communicate in English, with friends, teachers, families and local people. You will gain English language skills which you will keep for life.

English: the language of Taylors College

Strong English language skills are necessary for success in your chosen Taylors program. The TELP program, delivered in 12 week terms, is specifically designed to provide language training for academic study. Our teachers are fully trained English Language Teaching professionals, who will assist you in a caring and supportive classroom atmosphere.

TELP focuses on:

·Language studies   ·Formal writing styles

·Note taking     ·Assignment writing

·Intensive listening  ·Reading

Progressing to our High School or Foundation Programs

Upon completion of TELP, you do not take an IELTS test before you begin our High School or Foundatin programs.

TELP term dates

Students are encouraged to enroll(注册)at the start of a term; however, TELP courses allow for entry every four weeks.

2010 dates

·18 January –9 April          ·12 April –2 July

·5 July-24 September       ·27 September-17 December

2010 Summer School

·20 December-14 January 2011

60.The TELP program         .

A.is popular and thought highly of by students

B.is aimed at those who have passed an IELTS test

C.makes sure students have a communicative atmosphere

D.makes sure students learn the English language for four months

61.It can be inferred from the text that       .

A.TELP courses permits students to have lessons at any time

B.start date of the first term in 2011 is probably January 17th

C.students who study from 20th December to 14th January have cold weather

D.High School and Foundation programs at Taylors college have no entry requirements

62.What information will probably be provided following TELP term dates?

A.TELP fees            B.TELP descriptions     

C.TELP courses               D.TELP term dates in 2011

多项选择题