问题 问答题

(1)利用图中所示的装置可以研究自由落体运动.实验中需要调整好仪器,接通打点计时器的电源,松开纸带,使重物下落.打点计时器会在纸带上打出一系列的小点.打点计时器接在频率为50Hz的交流电源上,下图为实验中打出的一条纸带,从起始点O开始,将此后连续打出的7个点依次标为A、B、C、D….该重物下落的加速度为______m/s2.(结果保留两位有效数字)

(2)如图是小球做平抛运动的闪光照片,图中每个小方格的边长都是0.54cm,已知闪光频率是30HZ,那么重力加速度g是______m/s2,小球在A点时的竖直方向速度是______m/s.

答案

(1)设AB、BC、CD、DE、EF、FG的位移分别为x1、x2、x3、x4、x5、x6

则 a=

(x4+x5+x6)-(x3+x2+x1)
9T2
=
0.025+0.021+0.018-0.013-0.01-0.006
9×0.022
=9.60m/s2

(2)在竖直方向上△y=gT2,所以g=

△y
T2
=9.72m/s2

中间点在竖直方向上的速度vy=

0.0054×4
2T
=0.32m/s,则vyA=vy+gT=0.64m/s.

故答案为:(1)9.6;(2)9.72;0.648

阅读理解

Joe, an outgoing girl, is from a rich family. Therefore she can afford almost everything. But Joe’s parents are too busy to spend enough time with her, which makes Joe more than lonely. So, she always goes to WeChat. On WeChat, she can do a lot of things like buying things, reading articles, and making friends with those she either knows or not.

She uses the name Linda on WeChat and has made a lot of friends there. Last year Joe made a foreign friend on WeChat. Her name was Catherine and she lived in Sydney. Catherine once sent a picture of “herself”: a tall, good-looking young woman with big eyes. Catherine and Joe were both interested in rock music and modern dance. So, they liked each other very much.

When Joe’s father told her that he was meeting a client in Sydney this summer, she went with him to give Catherine a surprise for her birthday. When Joe came to Catherine’s house in Sydney, she found that her foreign “girlfriend” was a ten-year-old boy named Jim! What a surprise!

小题1:Joe spends time on WeChat to          .

A.make friends

B.kill time

C.read articles

D.buy things小题2:What is the real name of Joe’s “girlfriend”?

A.Catherine

B.Joe

C.Jim

D.Linda小题3:From this article, we can say          .

A.Everyone uses his real name on WeChat

B.On WeChat, we can only talk with Chinese people.

C.On WeChat, we can talk with Chinese people in Australia.

D.Joe’s father went to Sydney to meet Joe’s friend Catherine.小题4:What’s the best title of the passage?

A.A Sad Girl

B.A Real Surprise

C.A Special Foreigner

D.A Boy Called Jim

单项选择题 A1/A2型题