把质量为2kg的物体竖直向上抛出,初速度是12m/s,经1s物体到达所能达到的最

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问题:

把质量为2kg的物体竖直向上抛出,初速度是12m/s,经1s物体到达所能达到的最高点.设空气阻力大小不变,则前2s内物体重力势能的增加量是多大?空气阻力对物体做了多少功?(g取10m/)

考点:动能定理
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Visitors to this country are normally admitted for six months, but foreign students can usually stay for one year. They must (51) an educational institution, and they are required to study for a minimum of fifteen hours a week on a (52) course. Prospective students have to show that they can afford their studies, and that they have sufficient (53) resources to support themselves (54) in this country.

In order to work here the foreigner needs a work permit, (55) must be applied for by his prospective employer. The problem here is that the Department of Employment has the right to grant or (56) these permits, and there is little that can be done (57) it; it would be extremely unwise for a foreign visitor to work (58) a permit, since anyone doing so is liable to immediate deportation (驱逐出境). There are some people from the Common Market countries, who are often given (59) residence permits of up to five years. Some other people, such as doctors, foreign journalists, authors and others can work without permits, and foreign students are normally allowed to (60) part-time jobs while they are studying here.

57().

A.for 

B.on 

C.about 

D.with

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颅咽管瘤属于神经上皮组织肿瘤。

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春秋末年开凿的邗沟是我国最早的运河,它沟通的水系是()。

A.黄河和海河

B.海河和淮河

C.淮河和长江

D.长江和钱塘江

题型:问答题

你知道吗,同一纬度地区,相对位置偏东的地点,要比偏西的地点[ ]

A、先看到日出

B、后看到日出

C、时刻晚一些

D、时刻相同

题型:问答题

期货交易所会员的保证金不足时,应当及时追加保证金或者自行平仓。会员未在期货交易所规定的时间内追加保证金或者自行平仓的,期货交易所应当将该会员的合约强行平仓,强行平仓的有关费用和发生的损失由该会员承担。( )

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