问题 选择题

如图所示,装有大猩猩的箱子放在大磅秤上.坐在箱中的大猩猩用力向上推箱顶时,下列判断正确的是(  )

A.大猩猩对箱底的压力增大,磅秤示数减小

B.大猩猩对箱底的压力不变,磅秤示数增大

C.大猩猩对箱底的压力增大,磅秤示数不变

D.大猩猩对箱底的压力增大,磅秤示数增大

答案

答案:C

题目分析:(1)大猩猩没推箱顶时,大猩猩对箱底的压力等于大猩猩的重力.

大猩猩用力向上推箱顶时,大猩猩给箱顶一个向上的力,根据物体间力的作用是相互的,箱顶给大猩猩一个向下的力,箱底受到的压力等于大猩猩的重力和箱顶给大猩猩作用力之和.所以大猩猩对箱底的压力增大.

(2)大猩猩是否推箱顶,大猩猩和箱子的总重是不变的,所以箱底对磅秤的压力不变,示数不变

点评:放在水平面上的物体对水平面的压力大小等于物体的重力,但是这两个力不是相同的力,因为作用点是不同的

阅读理解

In June, 2007, a group of students from eight high schools in Winnipeg, the capital of Canada’s Manitoba province, will begin test-launching (试发射) a satellite the size of a Rubik’s cube.

The one-kilogram Win-Cub satellite, named for its home city and its shape, will be put into low orbit. Once in space, it can perform for a few months or up to several years, communicating information that could help find the signs of earthquakes.

There are 80 similar satellite projects worldwide, but this is the first high-school based program of its kind in Canada. 30 Manitoba high school students are having a hand in designing and building the satellite, in cooperation with aerospace (航空航天的) experts and 10 students from the University of Manitoba, and with support from two other organizations.

The Win-Cube project is not something that goes on a piece of paper; it is real-world engineering, allowing high school students to have an opportunity to learn more about the exciting world of engineering through their participation in this challenging program. It is also taken as a wonderful example of the unique partnerships within Manitoba. Designing, building and launching a satellite with high-school participation will bring this world-class educational project into reality and Manitoba closer to space

“These Manitoba high school students deserve congratulations for their enthusiasm, innovation (创新), and a strong love for discovery,” said Education, Citizenship and Youth Minister Peter Bjomson. “We want to make science more relevant, interesting and attractive to high school students by showing them how classroom studies can relate to practical experience in the workplace or, in this case, in space,” Bjomson added. 

The Win-Cube program is mainly named at inspiring a strong desire for discovery on the part of the students. It also shows Manitoba’s devotion to research and innovation and the development of a skilled workforce—all important drivers of knowledge-based economic growth.

1. According to the passage, the Win-Cube satellite is        .

A. named after Manitoba and its shape               

B. intended for international communication

C. designed like a Rubik’s cube both in shape and size 

D. challenged by university students around the world

2. According to Mr. Bjomson,        .

A. those Manitoba high school students are worth praising

B. the study of space can be practically made in classrooms

C. Manitoba high schools are famous for the study of space

D. scientific research is too far away from high school students

3. The primary purpose of the project is to        .

A. find the early signs of earthquakes            

B. relate studies to practical

C. help high school students study real-world engineering

D. inspire a strong desire for discovery among the students

4. Which of the following statements is WRONG?

A. In Canada there are 80 similar satellite programs in all.

B. These students will have an opportunity to learn more about engineering through the project.

C. These high school will have a strong love for discovery and be interested in science.

D. This Win-Cube program is very successful in Canada.

5. The best title for this passage may be        .

A. Manitoba School                        B. Win-Cube Program

C. Space Co-operation                       D. Satellite Launching

问答题 简答题