问题 填空题

电磁打点计时器使用______电源.利用打点计时器《探究小车的速度随时间变化的规律》,如图2给出了某次实验中的纸带,其中0、1、2、3、4、5、6都为计数点,每相邻两个计数点的间还有四点(未画出),电源频率50Hz从纸带上测得:X1=1.50cm,X2=2..00cm,X3=2.50cm,X4=3.00cm,X5=3.50cm,X6=4.00cm.

(1)通过纸带分析可知,小车的速度在______(填“增大”或“减小”);

(2)每相邻两个计数点的时间间隔是______s;

(3)计数点0到计数点6的平均速度是______m/s;

(4)计数点4的速度为______m/s.

答案

电磁打点计时器使用低压交流电源,通常的工作电压为 4至6V.

(1)由图示纸带可知,在相同时间内的位移逐渐增大,知小车做加速运动,速度在增大.

(2)电源频率为50Hz,打点时间间隔为0.02s,每相邻两个计数点的间还有四点(未画出),则每相邻两个计数点的时间间隔t=0.02×5=0.10s.

(3)计数点0到计数点6之间的平均速度v=

x1+x2+x3+x4+x5+x6
6t
=
0.015+0.02+0.025+0.03+0.035+0.04
6×0.1
≈0.28m/s

(4)计数点4的速度v4=

x35
2t
=
0.025+0.03
2×0.1
=0.33m/s;

故答案为:低压交流;(1)增大;(2)0.10;(3)0.28;(4)0.33.

阅读理解

Do you have any skiing equipment you no longer need? A ski school in the far north of India could put it to good use.

In March we published a photo story about the extraordinary Zsnskar region in northern India,which is cut off from the outside world for more than seven months of the year,and only accessible (可通行的)via a frozen river.We also included information about the limited use of skiing in the region and the recent creation of the Zanskar Ski School:

“Despite the difficulties of travelling through the region when the snow comes,skiing hasn’t traditionally been used as a means of transport by the locals,largely because trees don't grow here, so there is little in the way of raw materials from which to make skis.In 1995, a group of British scientists in the region noticed the lack of skis and one of them returned to set up the Zanskar Ski School in Padam.The school provides lessons for a small fee and rents skis to the local people. Among the benefits that the school hopes to bring are improved education—children often find it difficult to get to school through the deep snow—and the possibility of offering ski tours to tourists in the future.So far,more than 300 local people have received training,and local doctors and policemen regularly borrow skis.”

But what we weren't able to include in the article is that the ski school is always on the look out for old skiing equipment—particularly of a size suitable for children—and, I thought. Now the European ski season is drawing to a close,there might be a few of you out there who have some old equipment you'd like to see go to a good home.If that's the ease you can get in touch with the school via their website www.zanskarski school.org.

小题1:What's the purpose in writing the text?

A.To raise money to develop this area

B.To attract more tourists to the area

C.To appeal to more locals to attend the school

D.To ask people to give away their skis to the school小题2:The local people don't use skiing to go about because             .

A.it is against the local custom

B.they don't have the wood to make skis

C.trees are in the way of the skiing route

D.it is dangerous to go skiing in this region小题3: Who would be the most helpful to the school now?

A.People having old skiing equipment.

B.Students in the Zanskar Ski School

C.Locals in Zanskar region

D.Tavellers enjoying skiing小题4:What can be the best title for the text?

A.An extraordinary region in India

B.A home for old skis

C.A good means of transport

D.A popular sport—skiing

单项选择题