问题 选择题

如图跳伞运动员打开伞后经过一段时间,将在空中保持匀速降落.已知运动员和他身上装备的总重力为G1,圆顶形降落伞伞面的重力为G2,有8条相同的拉线,一端与飞行员相邻(拉线重力不计),另一端均匀分布在伞面边缘上(图中没有把拉线都画出来),每根拉线和竖直方向都成300角.那么每根拉线上的张力大小为(  )

A.

B.

C.

D.

答案

答案:A

以人为研究对象,把8根绳子的拉力正交分解,所有拉力水平方向的合力为零,竖直方向的合力和重力平衡,即解得F= 

填空题
阅读理解

I have been a student at Bentley College in Waltham for some time now, so I have a lot of experience and know how things work at Bentley. As a freshman(新生)at Bentley College you will be living in the Tree Dorms, Slade Hall or Miller Hall. I would highly suggest that you choose to live in the Tree Dorms because this is where most fresh-men are going to be living. There will be a lot of activities going on in the building and you will meet lots of people. Slade Hall is next to the parking lot(停车场)and not far from the Tree Dorms, so that would be your second choice. As Miller Hall is small and far away, it would be my last choice for freshmen housing. If Bentley offers you the chance to live with second or third year students you’d better refuse their offer and live with freshmen. Living with your classmates will make the transition (过渡) into college life a lot easier.

As a freshman your classes should be easy. After freshman year your classes will become a lot more difficult, so I advise that you get down to business early in the first year. There are two very easy things you can do to increase your knowledge as a freshman. The first is to just go to class and the second is to always do your homework. I also highly advise that you do it on your own and try to stay disciplined(遵守纪律的). It is too easy to put your homework away and then get really behind and not be able to learn everything before a mid-term or final exam.

小题1:The author advises freshmen to live in the Tree Dorms because ___________.

A.it is across the parking lot from Slade Hall

B.it is small and quite far away from the playground

C.there are many second and third year students there

D.there are many freshmen and more activities小题2:Where is Slade Hall?

A.Near Miller Hall.

B.Far from Tree Dorms.

C.Beside the car park.

D.Near the classrooms.小题3:According to the author, how can freshmen improve knowledge?

A.Remember to do homework by discussing it with others.

B.Finish homework and go to class every day.

C.Try to spend more time in the library.

D.Be able to learn something before a mid-term or final exam.小题4:The author writes the passage to ___________.

A.tell new students how to get used to college life

B.tell new students about their teachers and dormitory

C.show the differences between college and high school

D.tell readers about some funny things at Bentley College