问题 选择题

如图所示,物体在长度相等的细绳AO、BO的作用下处于静止状态,现将B点向右移动一小段距离,重新平衡后,则(    )

A.两绳的拉力的合力变大

B.两绳的拉力的合力不变

C.AO绳的拉力与重力的合力变小

D.BO绳的拉力与重力的合力不变

答案

答案:B

题目分析:对点O受力分析知,点O受两绳的拉力和物体的重力,且三个力平衡,将B点向右移动一小段距离,两绳间的夹角变大,重新平衡后,仍满足两绳的拉力的合力与物体的重力是平衡力,得两绳的拉力的合力不变,A错,B对;由平行四边形定则知,因两绳间的夹角变大,所以两个绳的拉力都变大,由三力平衡的知识知任两个力的合力与第三个力是平衡力,得到AO绳的拉力与重力的合力即是BO绳的拉力将变大,C错;BO绳的拉力与重力的合力即是AO绳的拉力将变大,D错。

点评:学生应画出O点的受力示意图,据图去分析问题。

单项选择题
阅读理解

When I decided to quit my job as a wedding photographer, I was in my late twenties, fresh from my divorce from Bob who had left me empty and confused. I decided to leave the US and travel. I had no savings, plus more than $5,000 in debt. What I did have were two sponsored tasks as a travel photographer- and with that along, I thought, it would be easy.

My first experience was a road trip from Toronto to Las Vegas, paid for by a car delivery service. Other trips followed and then I started a travel blog (博客). It was intended to be my calling card for assignment travel photography. Yet even with my blog and past experience, email after email I sent to publications, trying to get work, went unanswered. When they did get in touch, editors told me that I had no chance of making a career with travel photography. While I struggled to get on the path that I wanted, and as I expanded my blog to help get me there, I found myself wearing the hat of a full-time blogger.

Luckily, I got in at the right time. It was 2010,and the travel industry was just starting to turn its attention to bloggers. As I never could have predicted, my blogging-not my photography-did take me around the world successfully. At first,I thought it was for personal reasons, but I realized later that it was for free marketing for my blogging.

Within two years, I was being asked to speak at travel blogging conferences, which helped me to raise a network of friends around the world. Even more meaningful, however, was when I saw that my travels were also helping other people. My blog and social media followers saw that I chased my dreams and told me over and over again how they needed that kind of example, which was absent in their lives elsewhere.

小题1:After the author quit her job, she decided to ______.

A.divorce her husband

B.be a wedding photographer

C.pay off all her debt

D.go travelling abroad小题2: What can we learn about the author from the 2nd paragraph?

A.She paid money to a car delivery agency for a road trip.

B.She realised his dream of becoming a travel photographer.

C.She got a job as an editor in a publishing house.

D.She finally became a professional blogger unintentionally.小题3:The author believed her success mainly resulted from ______.

A.her personal reasons

B.her photographing skills

C.free marketing for blogging

D.booming of travel industry小题4: What did the author think of her two years' work?

A.Inspiring.

B.Appealing.

C.Interesting.

D.Challenging.