问题 实验题

(7分)(1)“验证机械能守恒定律”的实验可以采用图所示的甲或乙方案来进行.

比较这两种方案,________(选填:“甲”或“乙”)方案好些,理由是___________________________.

(2)下列有关实验的描述中,正确的是_________.

A.在"验证力的平行四边形定则"实验中,拉橡皮筋的细绳应稍长一些

B.在"探究弹簧弹力与其伸长量"关系的实验中,作出弹力和弹簧长度的图象也能求出弹簧的劲度系数

C.在"探究功与速度变化的关系"实验中,需要求出打点纸带的平均速度

(3)在探究“加速度与力、质量的关系”的活动中:

①某同学将实验器材组装如图所示。在接通电源进行实验之前,请你指 出该装置中的错误或不妥之处:

                       

②改正实验装置后,该同学顺利地完成了实验。下图是他在实验中得到的一条纸带,图中相邻两计数点之间的时间间隔为0.1s,由图中的数据可算得小车的加速度a为       m/s2.(结果取两位有效数字)

答案

(1) 甲 机械能守恒条件是只有重力做功,甲方案摩擦阻力较乙方案小;(2)AB ; (3) ①.打点计时器不应使用干电池,应使用交流电源;实验中没有平衡小车的摩擦力;小车初始位置离打点计时器太远     (只要答出其中的两点即可)  ②0.19~0.20内均正确

题目分析:(1)选择合适的实验装置,首先明确实验原理以及产生误差的原因,要从有利于减小实验误差和便于操作的角度进行选择.机械能守恒的前提是只有重力做功,实际操作的方案中应该使摩擦力越小越好.故甲方案好一些,因为这个方案摩擦阻力较小,误差小,操作方便,实验器材少.

(2)为了能准确的画出拉力的方向,拉橡皮筋的细线应稍长一点,便于找出两个距离较远的点确定方向,故A正确;由可知,F与x成正比,故作出图象后,图象的斜率为劲度系数,故B正确;在探究功和速度变化关系时,由求出速度,不需求出平均速度,故C错误.

(3)①由图可知,打点计时器不应使用干电池,应使用交流电源;实验中没有平衡小车的摩擦力;小车初始位置离打点计时器太远,无法得出足够多的点进行分析.

②采用逐差法求加速度,

单项选择题
写作题

阅读下面的短文,然后按照要求写一篇150词左右的英语短文。

“Can I see my baby?” asked the happy new mother. The bundle(婴儿包)was placed in her arms and when she moved the fold of cloth to look upon his tiny face, she gasped-the baby has been born without ears. Time, however, proved that the baby’s hearing was perfect except his appearance.

One day when he rushed home from school and threw himself into his mother’s arms, he cried out bitterly, “A boy, a big boy… called me a f-…freak(怪人).” She sighed, knowing that his life was to be endless of heartbreaks.

He grew up, handsome and popular with his fellow students. He developed a gift for literature and music. But for his misfortune, he might have been class president.

The boy’s father had a talk with the family doctor. “Could nothing be done?” “I believe we could graft(移植)on a pair of outer ears, if they could be donated(捐献),”the doctor decided. So the search began for a person who would make such a sacrifice a young man. Two years went by. Then, “You’re going to the hospital, son. Mother and I have someone who will donate the ears you need. But it’s a secret,” said the father.

The operation was a brilliant success. His talents blossomed (开花)into genius. School and college became a series of successes. Later he married and entered the diplomatic(外交)service. “But I must know!” he urged his father. “Who gave so much for me? I could never do enough for him.”

“I do not believe you could,” said the father, “but the agreement was that you are not to know….not yet.” The years kept the secret, but the day did come…. one of the darkest days that ever pass through a son. He stood with his father over his mother’s casket(棺材).Slowly and softly, the father stretched forth a hand and raised the thick, reddish-brown hair to let out the secret.

写作内容

以约30个词概括这个感人的故事

以约120个词,请就 “在受别人的帮助中,学会了帮助别人”的话题写一篇英语短文,表达你内心的感受,并包括如下要点:

1)你看完这个故事后,你如何评价这位母亲的无私行为;

2)请以你的日常生活经历的事情为例,说明别人的善良行为对你的影响;

3)你的感想。

写作要求

1. 作文中可使用自己的亲身经历或虚构的故事,

2.可以参照阅读材料的内容,但不得直接引用原文中的句子;

3. 无需标题

【评分标准】句子结构准确; 信息内容完整; 篇章结构连贯。