问题 问答题

(1)如图是验证力的平行四边形定则装置,将一根橡皮筋的一端固定在A上.第一次通过细线悬吊4个钩码时,橡皮筋的另一端被拉伸到O处(图甲);第二次在木板上固定了两个光滑小轮B和C,细线通过两轮分别悬挂2个和3个钩码,发现橡皮筋沿AO方向伸长但另一端O′与 O还未重合(图乙).

①为了使O′与 O点能够重合,他应该将小轮B、C适当向______(填“上方”或“下方”)移动;

②实验过程除记录橡皮筋与细线结点的位置O外,还需记录______ 和______.

(2)用如图甲的装置验证机械能守恒定律.

①除了图丙所示的实验器材,以及学生电源、导线和电键之外,还需要什么器材:______(填“天平”、“秒表”或“刻度尺”).

②请完成下列主要实验步骤:

A.将打点计时器接到学生电源的______(填“直流”或“交流”)输出端;

B.______,释放悬挂纸带的夹子,计时器打出一条纸带.

③图丁是该实验中得到的一条纸带,两个计数点间的距离数据如图,时间间隔T=0.1s.则D点对应的速度vD=______.(计算结果保留3位有效数字)

④由于______使机械能有损失,得出的实验结果,重锤重力势能减少量△Ep______(填“小于”、“等于”或“大于”)动能的增加量△Ek

答案

(1)①由乙图可知,两个分力的大小不变,要使其合力增大,应该减小两分力的夹角,故该将小轮B、C适当向下方移动.

故答案为:下方.

②根据实验原理可知需要根据两方分力的大小和方向做平行四边形,故需要记录分力的大小和方向,大小是通过记录钩码个数来实现的,而方向是通过记录细线方向来记录的.

故答案为:钩码个数,细线方向.

(2)①根据实验原理可知,该实验需要测量物体下落的高度,因此需要的仪器是刻度尺.

故答案为:刻度尺.

②根据打点计时器的工作原理可知,它使用的是交流电源;在具体操作中,为了使打点稳定,同时为了提高纸带的利用率,实验时先接通电源,然后再释放悬挂纸带的夹子.

故答案为:交流,接通打点计时器电源.

③匀变速直线运动中,时间中点的速度大小等于该过程中的平均速度大小,因此有:

vD=

xCE
2T
=
(0.167+0.215)m
2×0.1s
=1.91m/s

故答案为:1.91m/s.

④由于物体下落过程中不可避免的要克服阻力做功,因此重力势能没有全部转为动能,故最终重锤重力势能减少量△Ep大于动能的增加量△Ek

故答案为:阻力做功,大于.

阅读理解

阅读理解。

     Thackeray was born into a comfortably secure upper-middle-class family, and brought up to expect the

leisured life of "gentleman". However, partly though bad luck and bad financial (财政的) advice, partly through

his own profligacy (荒废) in early youth-he was Cambridge and for some years afterwards a compulsive (上

瘾的) gambler-he had been left with nothing to depend on but his brains and energy. He dreamed of writing a

great novel; but he realized that while he dreamed and wasted time. Writers whom he considered to be nobodies,

such as Bulwer-Lytton,were writing best sellers.

     Writing had not been his first choice of profession. To please his mother he spent some months, studying

law,but his earliest wish was to be a painter. He studied art in London and Paris before deciding that his talent

was too small for him to be anything but an amateur (业余的) painter, though he continued to draw

professionally, and illustrated (给…画插图) most of his own novels He then turned to journalism. In 1836,

while he was still struggling to make his way, he married penniless girl of eighteen, strongly against his mother's

will.

     With considerable courage, Thackeray began to make a living for his growing family from various

contributions to any newspapers and magazines that would take his work often he did not know where the next

five pounds was coming from Isabella Thackeray gave birth to three daughters,the second of whom died as a

child, hut after the birth of the third, in 1840, she became incurably mad and had to be cared fat away from her

family for the rest of her long life-she outlived her husband by over thirty years.

     This tragedy deeply affected Thackeray. It was, too, an extra financial load and for some years he was

forced to part with his daughters, who were brought up by his mother in France. While he struggled to make

a living in London, still chiefly by Journalism. His chances as a novelist seemed poor: his short novel Barry

Lynden, published serially in Fraser's Magazine in 1844 made so little impression oil the public that it was not

published in book form until twelve years later.

1. Thackeray was born into a family _____.

A. that had bad luck

B. that he could not rely on

C. that was quite rich

D. that expected him to be a writer

2. What did his mother want him to study?

A. Art

B. Law

C. Writer

D. Journalism

3. After he got married, Thackeray made a living by _____.

A. writing best sellers

B. drawing and illustrating his own novels

C. publishing a book which made him famous

D. writing for newspapers and magazines

4. After he got married, Thackeray made a living by _____.

A. writing best sellers

B. drawing and illustrating his own novels

C. publishing a book which made him famous

D. writing for newspapers and magazines

选择题