问题 实验题

在验证力的平行四边形定则的实验中,需要将橡皮条的一端固定在水平木板上,另一端系上两根细绳,细绳的另一端都有绳套,实验中需用两个弹簧秤分别钩住绳套,并互成角度的拉橡皮条。某同学认为实验过程中应该注意以下几项:

A.两根细绳必须等长

B.橡皮条应与两绳夹角的平分线在同一直线上

C.在使用弹簧秤时要注意使弹簧秤与木板平行

D.要使每次合力与分力产生相同的效果,必须每次将橡皮条拉到同样的位置其中正确的是_____.(填入相应的字母)。右图是甲、乙两位同学在“验证力的平行四边形定则”的实验所得到的实验结果,若用F表示两个分力F1、F2的合力,用F′表示F1和F2的等效力,则可以判断________(填“甲”或“乙”)同学的实验结果是符合事实的.

答案

正确的是   C、D       (填入相应的字母)。

判断__甲______(填“甲”或“乙”)同学的实验结果是符合事实的

此题涉及力学实验验证力的平行四边形定则。两根细绳提供的拉力要平行于木板,保证力的方向平行于木板。C答案正确。力的大小与细线的长短无关,所以细绳不必等长。A答案错误。橡皮条应该在两个分力组成的平行四边形的对角线,对角线不一定沿角平分线,所以B答案错误。两次拉动,要产生相同的效果,即橡皮条长度相同,伸长的方向也应该相同,所以要将橡皮条拉到同一点。D答案正确。用一个力拉的时候,一定要沿着橡皮筋的方向,所以甲的结果正确。本题考查方式灵活。

阅读理解

     To some people, happiness is something to do with simplicity, and it is the ability to extract pleasure

from the simplest things-such as a peach stone (桃核). It is obvious that it has nothing to do with success.

     For Sir Henry Stewart, it was certainly successful. I remember some ten years ago when he was made King's Counsel, Amos and I went to congratulate him. We smiled happily; he merely looked as miserable

as though he'd received a punishment. He took his success as a child does his medicine. And not one of

his achievements brought even a sign of a smile to his tired eyes.

     I asked him one day what it was like to achieve all one's ambitions. He looked down at his roses and

went on watering them. Then he said, "The only value in achieving one's ambitions is that you then realize

that they are not worth achieving."

     Yesterday, I was passing his house and he called me, "Come and see, Jan. Look! I have done it at last! "There he was, holding a small box of earth in his hand. I observed three tiny shoots out of it.

     "And there were only three!" he said, his eyes laughing to heaven.

     "Three what?" I asked.

     "Peach stones," he replied."I've always wanted to make peach stones grow, even since I was a child,

when I used to take them home after a party, or as a man after a banquet. And I used to plant them, and

then forgot where I planted them.But now at last I have done it. I had only three stones, and three shoots," he counted.

     Then Sir Henry ran off, calling for his wife to come and see his achievement-his achievement of

simplicity.

1. From what fact could we see Sir Henry was successful?

A. He felt happy from the simplest things.

B. He was made King's Counsel.

C. He was able to make the peach stones shoot.

D. He didn't take his success seriously.

2. The author compares Sir Henry's attitude towards his success to a child's taking medicine________.

A. to show that Sir Henry felt miserable when he was promoted

B. to prove that Sir Henry didn't want to be successful

C. to suggest that Sir Henry's future job would be hard to do

D. to tell us that Sir Henry took his success as a tiny thing in his life

3. According to Sir Henry Stewart, the value in achieving one's ambitions is________.

A. that he discovers it valueless

B. that he finds it worth his efforts

C. that he has achieved it

D. that he fails to realize it

4. The writer's opinion about Sir Henry's attitude towards success is________.

A. criticism  

B. disapproval  

C. admiration  

D. tease

填空题