理想实验是物理学发展过程中的一种重要的研究方法.伽利略曾设想了一个理想实验,如图

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问题:

理想实验是物理学发展过程中的一种重要的研究方法.伽利略曾设想了一个理想实验,如图所示(图中两斜面底部均用一小段光滑圆弧连接),下面是该实验中的一些事实和推论.

a.减小第二个斜面的倾角,小球在这斜面上仍然要达到原来的高度.

b.两个对接的斜面,让静止的小球沿一个斜面滚下,小球将滚上另一个斜面.

c.如果没有摩擦,小球将上升到原来释放时的高度.

d.继续减小第二个斜面的倾角,最后使它成为水平面,小球要沿水平面做持续的匀速运动.

(1)请将上述理想实验的步骤按照正确的顺序排列______.

(2)在上述的步骤中,属于可靠的事实有______,属于理想化的推论有______.(均只要填写序号即可)

考点:伽利略对自由落体运动的研究
题型:问答题

检验外购电子设备是否合格,一般要经过______后进行判断。

A.加电后一定时间的运行
B.联调后无负荷运行
C.联调后模拟负荷运行
D.直接投入应用环境

题型:问答题

“要想跑得快,全靠车头带”。今后3年我国铁路计划投资规模将超过3.5万亿元,按 2009年投资6000亿元测算,可以创造600万个就业岗位,消费钢材2000万吨、水泥1.2万吨,直接拉动GDP增幅1.5%。而加快高速铁路客运专线项目,还将带动新材料和信息产业的研发,橡胶、合成材料、电子电器行业、玻璃、铝、信息、计算机、精密仪器等产业的需求,预计对相关产业总产出的拉动为1万亿元。运用经济生活有关知识,结合材料说明加大铁路投资建设的意义。

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题型:问答题

已知:①CH3OH(g)+H2O(g)=CO2(g)+3H2(g),△H=+49.0kJ•mol-1

②CH3OH(g)+

1
2
O2(g)=CO2(g)+2H2(g),△H=-192.9kJ•mol-1

下列说法正确的是(  )

A.CH3OH转变成H2的过程一定要吸收能量

B.①反应中,反应物的总能量高于生成物总能量

C.根据②推知反应:CH3OH(l)+

1
2
O2(g)=CO2(g)+2H2(g)的△H>-192.9kJ•mol-1

D.反应②中的能量变化如图所示

题型:问答题

节流阀是安装在气动回路中,通过调节阀的开度限制()的控制阀。

A.速度

B.流量

C.压力

D.方向

题型:问答题

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

In recent years, there has been a dramatic increase in the range of media used to (71) information. Initially, communication was limited to simple forms of (72) such as voice and paper. This century, however, has witnessed the introduction of a greater variety of media types such as the telephone and visual forms of media. In the latter part of the century, this trend has accelerated and there is now a wide range of media types available to convey information. These advances provide a great opportunity for new developments in a range of areas such as education and commerce. However, there are also a number of problems associated with the growth of (73) in society. In particular, there is a great danger of creating information (74) . This problem can be seen, for example, in business where executives are required to make decisions based on an ever increasing variety and volume of information. (75) problems are also occurring in areas such as government, health care and education.

(73)是()

A.knowledge

B.computers

C.information

D.technology

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