问题 实验题

某同学设计了如图所示的装置来探究加速度与力的关系。弹簧秤固定在一合适的木板上,桌面的右边缘固定一支表面光滑的铅笔以代替定滑轮,细绳的两端分别与弹簧秤的挂钩和矿泉水瓶连接。在桌面上画出两条平行线MN、PQ,并测出间距d。开始时将木板置于MN处,现缓慢向瓶中加水,直到木板刚刚开始运动为止,记下弹簧秤的示数F0,以此表示滑动摩擦力的大小。再将木板放回原处并按住,继续向瓶中加水后,记下弹簧秤的示数F1,然后释放木板,并用秒表记下木板运动到PQ处的时间t。

(1)木板的加速度可以用d、t表示为a=____________。

(2)改变瓶中水的质量重复实验,确定加速度a与弹簧秤示数F1的关系。下列图象能表示该同学实验结果的是____________。

(3)用加水的方法改变拉力的大小与挂钩码的方法相比,它的优点是____________。

A.可以改变滑动摩擦力的大小

B.可以更方便地获取多组实验数据

C.可以比较精确地测出摩擦力的大小

D.可以获得更大的加速度以提高实验精度

答案

(1)

(2)C

(3)BC

单项选择题 A3/A4型题
阅读理解

Aren’t they all our children?

There are few things in this life more difficult to experience than the loss of one’s child. Jim Wallis, in WHO SPEAKS FOR GOD, tells a story that happened during the war in Sarajevo. A reporter who was covering the violence in the middle of the city saw a little girl shot by a gunman.

The reporter rushed to the aid of a man who was now holding the child. He helped them both into his car and sped off to a hospital.  

“Hurry, my friend,” the man urged, “my child is still alive.” A moment or two later he pleaded, “Hurry, my friend, my child is still breathing.” A little later he said, “Hurry, my friend, my child is still warm.”

When they got to the hospital, the young girl was gone. “This is a terrible task for me,” the distraught man said to the reporter. “I must go and tell her father that his child is dead.”

He looked at the man in surprise and said, “I thought she was your child.”

The man replied, “No, but aren't they all our children?”

I think that is one of the great questions of our age that deserves an answer.

Aren’t they all our children? Those on our side of the border as well as those on the other side? Those of our nation no more or less than those of another?

Aren’t they all our children? The well-educated and the under-educated? The well-fed and the under-fed? Those who are secure and those who are at risk?

Aren’t they all our children? if we say yes, can we ever again pit them against each other? “If we have no peace,” said Mother Teresa, “it is because we have forgotten that we belong to each other.”

There may be no greater question for our generation. And how we answer that question will determine the shape of our world for years to come.

51. What was the reporter doing when the shooting took place?

A. Telling a story.          B. Having a meeting.  

C. Reporting an event.       D. Helping the wounded.

52. From the text we know the girl died        .

A. in the hospital              B. with nobody in front  

C. soon after the shooting      D. far away from her home

53. How many people experienced the sad story?

A. Three.              B. Four.  C. Five.   D. Six.

54. Which can best express the point of a yes to the question “Aren’t they all our children?”

A. Health.       B. Love.  C. Wealth.     D. Peace.