试题与答案

长为3L的杆水平放置,杆两端A、B系着长为3L的不可伸长且光滑的柔软轻绳,绳上套

题型:问答题

题目:

长为

3
L的杆水平放置,杆两端A、B系着长为3L的不可伸长且光滑的柔软轻绳,绳上套着一质量为m的小铁环.已知重力加速度为g,不计空气影响.

(1)现将杆悬在空中,杆和环均静止,如图甲,求绳中拉力的大小:

(2)若杆与环保持相对静止,在空中沿AB方向水平向右做匀加速直线运动,此时环恰好悬于A端的正下方,如图乙所示.求此状态下杆的加速度大小a.

答案:

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参考答案:对

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五块钱的故事

       ①5元钱能够干什么?那一天我突然问自己。我4岁的女儿听见了,大声地说可以买两支冰淇淋。我什么也说不出来,我想起了父亲和5元钱的故事。

       ②那一年父亲上完小学,并以优秀的成绩考取了县一中。正当他满怀希望地迎接新学年到来的时候,我爷爷对他说,别上了,在家里割草吧。父亲的梦一下子被打碎了,他整日地哭泣,并拒绝干任何事情。爷爷没有办法。最后说,你自己挣够学费,你就上。

       ③学费是5元,对今天的孩子来说只是两支冰淇淋的价格,但对30年前的父亲来说是一笔不小的数目。爷爷说这句话其实压根儿就没想让父亲去上学。

       ④父亲沉默了好多天,最后他拿起镰刀,第一次向命运挑战。他冒着盛夏的(kù  rè)__________

 __,钻进田间地头给生产队割青草,有时一天下来割的青草捆起来比他人还高,足有100多斤。100斤青草,生产队给算5个工分。那一年一个工分大约合5分钱,这样父亲最多的一天能挣到0.25元了,20多天就能挣够5元钱。他一遍又一遍地计算着,仿佛一个登山者不断地抬头看着距离山顶的路。最后,父亲离自己的目标只有(yī  bù  zhī  yáo)____________了,再割100斤青草,就凑够5元钱了。

       ⑤那一天早上父亲起得特别早,他激动地走在田间小道上,仿佛看到了自己已身处课堂。那一天特别炎热,但父亲已顾不得了,拼命地割着草。汗水湿透了他的衣服,最后他感到头晕脑胀,迷迷糊糊举起镰刀一下子割在了自己腿上,血从他的腿上流出,他倒在了地上。等他从病床上爬起来的时候,县一中已开学半个多月了。而爷爷也说,为了给他治腿伤,花了十几块钱,学上不成了。

       ⑥在我的记忆中,每当我跟父亲要钱的时候,他从来没有说过不给。甚至在外求学时,我想喂一喂肚子里的馋虫却说谎要订复习资料的时候,父亲也从未问过我什么,而是即使东借西凑也把钱如数寄来。直到有一天,父亲给我讲了5元钱的故事,我后悔地跑到校外树林里,把头撞到一棵小树上,让疼痛减轻我内心的愧疚。从那时起,在校期间我便再也没有吃过食堂以外的任何食品了。

       ⑦我感谢父亲给我讲的故事,让我再告诉我的女儿吧,也许长大了她会说5元钱能做很多事情,甚至,能改变一个人的一生。

1、在文中的拼音处写上汉字。

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(2)________________________________________________________;

(3)________________________________________________________。

5、第⑥节中既写父亲总是满足我用钱的要求,即使东借西凑也“如数”给我;又写父亲给我讲了5元钱的故事,是否矛盾,请说明理由:____________________________________________________________

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6、谈谈你对结尾段的理解:__________________________________________________________________

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B.shortage

C.deficiency

D.deficit

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