问题 选择题

有一高度为H的田径运动员正在进行100m的国际比赛,在终点处有一站在跑道旁边的摄影记者用照相机给他拍摄冲线运动情况.摄影记者使用的照相机的曝光时间是△t,得到照片后测得照片中运动员的高度为h,运动员胸前号码布影象模糊部分的宽度是△L,由以上数据可以估算出(  )

(1)曝光时间△t内运动员的位移;      (2)运动员的冲线速度;

(3)100m内运动员的平均速度;        (4)100m比赛过程中运动员的加速度.

A.(1)(3)

B.(2)(3)

C.(2)(4)

D.(1)(2)

答案

(1)、(2)胸前号码上的模糊部分的宽度为△L,即为两次曝光时运动员的底片上的位移,根据运动员底片上的高度和实际高度的比例即可求得两次曝光的实际位移为:x=

H
h
△L,所以冲刺时的瞬时速度v=
x
△t
=
H△L
h△t
.故(1)、(2)均正确;

(3)100m内的平均速度等于总位移除以总时间,因无法求得时间,所以无法求出平均速度,故(3)错误;

(4)比赛过程中运动员的加速度是变化的,无法求出.故(4)错误.

故选D

选择题
阅读理解

阅读理解。

     If you know exactly what you want, the best way to get a job is to get specialized training. A recent

report shows that companies like graduates in such fields as business and health care who can go to work

immediately with very little on-the-job training.

     That's especially true of booming fields that are challenging for workers. At Cornell's School of Hotel

Administration, for example, bachelor's degree graduates get an average of four or five job offers with salaries

ranging from the high to low and plenty of chances for rapid advancement. Large companies especially like

a background of formal education coupled with work experience. But in the long run, too much specialization

does not pay off. Business, which has been flooded with MBAs, no longer considers the degree an automatic

stamp of approval. The MBA may open doors and command a higher salary initially, but the impact of a degree

washes out after five years.

     As further evidence of the erosion of corporate faith in specialized degrees, Michigan State's Scheetz cites

a pattern in corporate hiring practices. Although companies tend to take on specialists as new hires, they often

seek out generalists for middle and upper-level management. This sounds like a formal statement that you

approve of the liberal-arts (文科) graduate. Time and again labor-market analysts mention a need for talents

that liberal-arts majors are assumed to have: writing and communication skills, organizational skills, open-

mindedness and adaptability, and the ability to analyze and solve problems. David Birch, manager of the Boston

Red Sox, says that he does not hire anybody with an MBA or an engineering degree."I hire only liberal-arts

people because they have a less-than-canned way of doing things," says Birch.

     For a liberal-arts degree, students focus on some basic courses that include literature history, mathematics,

economics, science, human behavior and a computer course or two. With these useful and important courses,

you can feel free to specialize, "A liberal-arts degree coupled with an MBA or some other technical training is

a very good combination in the marketplace," says Scheetz.

1. The job market is in great need of people with _____. [ ]

A. special training in special fields

B. a bachelor's degree in education

C. formal schooling and work experience

D. an MBA degree from top universities

2. The underlined sentence in Paragraph 2 means _____. [ ]

A. an MBA degree does not help in future promotion

B. MBA programs will not be as popular as they are now

C. people will not forget the degree the MBA graduates have got

D. most MBA programs fail to provide students with a foundation

3. David Birch says that he only hires liberal - arts people because _____. [ ]

A. they will follow others' ways of solving problems

B. they can do better in bundling changing situations

C. they are well trained in a variety of specialized fields

D. they have attended special programs in management

4. The author supports the idea that _____. [ ]

A. on-the-job training is less costly in the long run

B. formal schooling is less important than job training

C. specialists are more expensive to hire than generalists

D. generalists will do better than specialists in management