如图甲所示,一根足够长的细杆与水平成θ=37°固定,质量为m=1kg的小球穿在细

题型:计算题

问题:

如图甲所示,一根足够长的细杆与水平成θ=37°固定,质量为m=1kg的小球穿在细杆上静止于细杆底端O点,今有水平向右的F作用于小球上,经时间t1=0.2s后停止,小球沿细杆运动的部分v-t图像如图乙所示(取g=10m/s2,sin37°=0.6,cos37°=0.8).试求:

(1)小球在0~0.2 s内的加速度a1和0.2~0.4s内的加速度a2

(2)0~0.2 s内水平作用力F的大小.

(3)撤去水平力后,小球经多长时间返回底部.

   

考点:从运动情况确定受力v-t图像
题型:计算题

(3分)下列实验操作不正确的是                   (填字母代号)。

A.在催化剂存在的条件下,苯和溴水发生反应可生成无色、比水重的液体溴苯。

B.将铜丝弯成螺旋状,在酒精灯上加热变黑后,立即伸入盛有无水乙醇的试管中,完成乙醇氧化为乙醛的实验。

C.醇中含有少量水可加入生石灰再蒸馏制得无水乙醇。

D.验证蔗糖的水解产物时,将蔗糖和稀H2SO4溶液混合,水浴加热使其充分水解,然后用稀的NaOH溶液使其呈碱性后,再滴加银氨溶液。F.验证溴乙烷水解产物时,将溴乙烷和氢氧化钠溶液混合,充分振荡溶液、静置、待液体分层后,滴加硝酸银溶液。

G.实验室蒸馏石油时温度计水银球插入石油中测量温度,收集60℃~150℃馏分得到汽油。

题型:计算题

Since the pre-historic times, man has had an urge to satisfy his needs. Be it hunger, shelter or search for a mate, he has always controlled the situations to his advantage. Probably this might be the reason why we humans are the most developed of all living species on the earth. As we climbed the steps of development, we somehow left behind common sense and logical thinking -- we forgot that we have stopped thinking ahead of time.

If you are hungry, what do you do? Get a piece of your favorite meal and stay quiet. Just like your stomach, even your mind is hungry. But it never lets you know, because you keep it busy thinking about your dream lover, favorite star and many such things. So it silently began to care about your needs and never let itself grow. When mind looses its freedom to grow, creativity gets a full stop. This might be the reason why we all sometimes think "What happens next?", "Why can't I think?" "Why am I always given the difficult problems?" Well, this is the result of using our brain for thinking of not-so-worthy things.

Hunger of the mind can be actually satisfied through reading. Now why reading and not watching TV? Because reading has been the most educative tool used by us right from the childhood. Just like that to develop other aspects of our life, we have to turn to reading. You have innumerable number of books in this world which will answer all your "How to?" questions. The interesting part of the book is stored in your mind as a seed. Now this seed is unknowingly used by you in your future to develop new ideas. The same seed, if used many times, can help you link and relate a lot of things, of which you would have never thought in your wildest dreams! This is nothing but creativity. More the number of books you read, your mind will open up like never before.

小题1:What is the function of the first paragraph?

A.To show humans are the most developed.

B.To introduce the topic of the passage.

C.To indicate people have different needs to satisfy.

D.To explain why people need to read.小题2:What does the author mean by saying "When mind looses its freedom to grow, creativity gets a full stop."

A.When mind keeps growing, creativity fully stops.

B.When freedom is lost, creativity gets a full stop.

C.When mind stops growing, creativity fully stops.

D.When growing is lost, creativity gets a flail stop.小题3:The paragraph following the passage is probably about ______.

A.how the pre-historic man feeds his mind

B.what other advantages reading brings

C.how to develop creativity

D.how to satisfy your mind by watching TV小题4: The author tends to tell us ______.

A.reading can satisfy your all needs

B.reading can result from creativity

C.reading can feed your mind

D.reading can realize your dreams

题型:计算题

制售假药,足以严重危害人体健康的

A.处2年以下有期徒刑或拘役,并处或者单处销售额50%至2倍罚金

B.处3年以下有期徒刑或者拘役,并处或单处销售额50%至2倍罚金

C.处3年以上10年以下有期徒刑,并处销售额50%至2倍罚金,或者没收财产

D.处10以上有期徒刑、无期徒刑或死刑,并处销售额50%至2倍罚金,或者没收财产

E.处10以上有期徒刑或无期徒刑,并处销售额50%至2倍罚金,或者没收财产

题型:计算题

重载输入流运算符>>必须使用的原型为

A.istream& operator>>(istream&,<类名>&);

B.istream& operator>>(istream,<类名>);

C.istream operator>>(istream,<类名>&);

D.<类名>operator>>(istream&,<类名>&);

题型:计算题

脚手架搭设后应经使用单位和()验收合格后方可使用,使用中应定期进行检查和维护。

A.业主单位

B.监理单位

C.设计单位

D.施工单位

更多题库