在“研究匀变速直线运动规律”的实验中,小车放在斜面上,车前端拴有不可伸长的细线,

题型:实验题

问题:

在“研究匀变速直线运动规律”的实验中,小车放在斜面上,车前端拴有不可伸长的细线,跨过固定在斜面边缘的小滑轮与重物相连,小车后面与穿过打点计时器限位孔的纸带相连,如图甲所示。起初小车停在靠近打点计时器的位置,重物到地面的距离小于小车到滑轮的距离。启动打点计时器,释放小车,小车在重物牵引下由静止开始沿斜面向上运动,重物落地后小车会继续运动一段距离,打点计时器在纸带上连续打下一系列点,图乙中a、b、c是纸带上的三段,打点的先后次序是a→b→c。(打点计时器使用的交流电频率为50 Hz)  

(1)根据纸带上所提供的数据,计算打c段纸带时小车的加速度大小为__________m/s2(结果保留两位有效数字)。方向与小车的运动方向__________(填“相同”或“相反”)。  

(2)打b段纸带时,小车运动的最大速度出现在b纸带中的__________(填图乙中的相邻两个字母)段。

考点:实验:探究小车速度随时间变化的规律
题型:实验题

3,5B.r2-PA.DA.T分光光度法测定水中银时,所用的十二烷基硫酸钠溶液浓度为()%水溶液。

题型:实验题
根据短文内容,从短文后的选项中选出能填入空白处的最佳选项.选项中有两项为多余选项.
     What is your favourite colour? Do you like yellow,orange,red? __1__Do you prefer grey and blue?
Then you are probably quiet,shy,and you would rather follow than lead. You tend to be a pessimist. At
least,this is what psychologists tell us,and they should know,because they have been seriously studying the meaning of colour preference,as well as the effect that colours have on human beings. __2__If you
happen to love brown,you did so,as soon as you opened your eyes,or at least as soon as you could see
clearly.
     __3__A yellow room makes most people feel more cheerful and more relaxed than a dark green one;
and a red dress brings warmth and cheer to the saddest winter day. __4__ A black bridge over the
Thames River,near London,used to be the scene of more suicides(自杀) than any other bridge in the
area-until it was repainted green. The number of suicide attempts immediately fell sharply. Perhaps it would have fallen even more if the bridge had been done in pink or baby blue.
     __5__It is an established fact that factory workers work better,harder,and have fewer accidents when
their machines are painted orange rather than black or grey.
A. On the other hand,black is depressing.
B. They tell us,among other facts,that we do not choose our favourite colour as grow up-we are born with our preference.
C. The rooms are painted in different colours as you like.
D. If you do,you must be an optimist,a leader,an active person who enjoys life,people and excitement.
E. Light and bright colours make people not only happier but more active.
F. Life is like a picture or a poem,full of different colours.
G. Colours do influence our moods-there is no doubt about it.


题型:实验题

“泛长三角”区域合作

题型:实验题

参照设备的生产能力大于被评估设备,应在参照设备售价的基础上,下调价格以符合被评估对象的实际情况。( )

题型:实验题

肠梗阻的四大共同表现是()

A.腹痛、肠型、呕吐、便闭

B.腹痛、呕吐、腹胀、便闭

C.便闭、腹痛、腹胀、肠音亢进

D.便闭、腹痛、肠音减弱、腹胀

E.腹痛、便闭、肠型、腹胀

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