如图所示,某同学利用竖直上抛小球的频闪照片验证机械能守恒定律.频闪仪每隔0.05

题型:实验题

问题:

如图所示,某同学利用竖直上抛小球的频闪照片验证机械能守恒定律.频闪仪每隔0.05 s闪光一次,图中所标数据为实际距离,该同学通过计算得到不同时刻的速度如下表.(已知当地重力加速度为9.8 m/s2,小球质量m=0.2 kg,结果保留3位有效数字)

时刻t2t3t4t5
速度(m/s)4.994.483.98 

(1)由频闪照片上的数据计算t5时刻小球的速度v5   m/s。

(2)从t2到t5时间内,重力势能增量ΔEp   J,动能减少量ΔEk   J。

(3)在误差允许的范围内,若ΔEp与ΔEk近似相等,即可验证机械能守恒定律。由上述计算得ΔEp   ΔEk(选填“>”、“<”或“=”),造成这种结果的主要原因是   

考点:实验:探究弹力与弹簧伸长的关系实验:探究小车速度随时间变化的规律实验:探究加速度与力、质量的关系实验:探究功与速度变化的关系
题型:实验题

小明家离学校432米,小红家离学校521米,小红家离小明家最远是______米,最近是______米.

题型:实验题

伴有胸痛剧烈的刺激性干咳宜选用:

A.喷托维林

B.苯佐那酯

C.可待因

D.右美沙芬

E.溴己新

题型:实验题

Jascha Richter once sang “don't need too much talking without saying anything” to reveal his lonely feeling in a crowd.

Dad always told me never to ever reveal my true opinions towards other people if such opinions are negative. He said this is the “Chu Shi Zhe Xue”, the philosophy of dealing with social network.

It seems that everybody here just follows this philosophy very, very well.

Friends. I would say that if I were given true friendship I would definitely treasure it with my greatest care. If I really regard someone as my close friend, I would never leave her alone whenever she's in need, either financially or mentally. And I always believe, as long as I treat people with whole-hearted honesty, I would have some rewards—at least, just ONE true friend of the same gender(性别).

Sometimes I just miss my friends in China. Perhaps when we became friends, we were still young, too young to have been polluted by any dirt in the society. But here, it is simply different. It seems that all of us have learnt how to SURVIVE in a foreign land and such an experience actually makes us learn how to extract (榨取) the most benefits from the surroundings in order to survive.

All are friends around me. I've looked through all the dark sides of their personalities and yet I have to pretend that I know nothing. THEY ARE GOOD. THEY ARE GOOD. AND WE ARE FRIENDS. And then I can make myself comfortable enough to talk to people I hate the most. And of course, they don't say any words truly from their hearts. Neither do I.

But, sometimes I just feel unwilling to talk to these people. Sometimes, I just want to be alone, quietly, without being forced to listen to their gossip or other useless words.

“Standing on a mountain high

Looking at the moon through a clear blue sky

I should go and see some friends         

But they don't really comprehend”

Jascha Richter expresses my feelings also.

67. 小题1:What do we know about the writer’s father according to this passage?

A.He is really a good philosopher.

B.He possibly gets on well with others.

C.He told the writer to reveal her true opinions.

D.The passage doesn’t tell us at all.68. 小题2:What’s the most probable reason the writer mentions Jascha Richter’s song twice in the passage?

A.She likes Jascha Richter’s song.

B.Jascha Richter is one of her friends.

C.The song expresses her feelings.

D.She uses it to perfects her article.69. 小题3:Which of the following statements about the writer is TRUE?

A.She is now living abroad but doesn’t enjoy the life there.

B.She absolutely believes in her father’s philosophy.

C.She shows a positive attitude towards her relationship with others.

D.She thinks highly of her friends by repeating “They are good”.70. 小题4:The writer mostly expresses her ______ in this passage.

A.happiness

B.homesickness

C.sadness

D.loneliness

题型:实验题

普光气田站控系统和中控系统无法实现()。

A.同时监视

B.同时操作

C.数据共享

D.数据无线传输

题型:实验题

能够抑制微管组装的药物是()

A.秋水仙素

B.长春花碱

C.鬼笔环肽

D.细胞松弛素

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