问题 问答题

某一时刻,所有的地球同步卫星(  )

A.向心力相同

B.线速度相同

C.向心加速度相同

D.离地心的距离相同

答案

A、同步卫星向心力由地球对卫星的万有引力提供,根据F=G

mM
r2
,虽然地球质量相同,但卫星质量可能不一样,故不同的卫星所需向心力不一定相同,故A错误;

B、根据万有引力提供圆周运动向心力可知,同步卫星的线速度大小相同,但考虑到线速度的矢量性,不能说线速度相同,故B不正确;

C、根据万有引力提供圆周运动向心力可知,同步卫星的向心加速度大小相同,但考虑到向心加速度的矢量性,不能说向心加速度相同,故C不正确;

D、根据万有引力提供圆周运动向心力可知,由于同步卫星的周期相同,其圆周运动的轨道半径亦相同,即同步卫星离地心的距离相同.D正确

故选D

阅读理解

University is generally regarded as one of the most important times in a person’s life, yet the function of this institution continues to arouse debate. Many believe that arts subjects are  too easy, that practical skills are more useful and that a chosen subject for study should be clearly linked to a career. However, this view is far too simplistic. Arts subjects are very difficult. They can prepare students for any number of careers as well as allowing the student to take time to make a decision. The function of the modern university is to cater to different types of student.

Arts subjects are not easy. For example, a degree in Literature is not an easy option. No question in a Literature class has a single, simple answer. Debate is conducted in a spirit of openness, texts are very closely analyzed and skills in close reading are developed. Literature is about language, our primary means of communication. Arts subjects require the same concentrated study as any other subject.

Arts subjects can prepare students for any number of careers. A degree in an arts subject teaches skills in well organized debates and defence of a position through the provision of evidence. These are applicable to many types of career. Law, for example. The point is that an undergraduate degree in any Arts subject trains the student in analysis and structure. Therefore, Arts graduates can pursue any number of careers.

Arts subjects allow the student to take time to choose a career. Love of the subject for its own sake may well be the initial motivation for the Arts undergraduate but because the subject they have chosen is not so clearly linked to a career they have time to reflect, making a decision only when they are absolutely certain. Students who pursue Arts subjects therefore have the leisure to make a carefully considered choice.

In conclusion, it is clear that Arts subjects are not a waste of time. They are flexible when it comes to relating them to a career and they allow the student to discover an appropriate career path. Many industries now acknowledge that a degree in Literature can be just as valuable as any other subject, especially when it is evident that Arts graduates tend to think more creatively. Not all undergraduates have clearly defined goals and not all subjects can be simply matched to a career. Acknowledging this difference should be the main function of a modern university

小题1: What does the author mainly argue in this article?   

A.Universities should be aware of diversity

B.Universities should focus on practical courses.

C.Arts courses should be promoted.

D.Arts subjects are inappropriate for work.小题2:What does the author imply about universities’ attitude to students?   

A.They need to be more understanding of students’ needs.

B.They need to keep out arts students.

C.They need to link courses to careers.

D.They need to offer more arts courses.小题3:The author suggests that technical subjects ____________.  

A.are more important than arts subjects.

B.are more useful to the modern world.

C.have equal value to arts subjects.

D.are not as important as arts subjects.小题4:From the article, we know skills acquired by arts undergraduates include___________. 

A.Perception and investigation

B.Technique and motivation

C.Appreciation and dedication

D.Analysis and structure 小题5:According to the author, the students choose arts courses initially because ___________. 

A.they are unsure about a career

B.they are interested in the subject

C.they hate technical subjects

D.they are creative people

单项选择题