贝贝和晶晶在探究牛顿第二定律的过程中分别采用了以下方案:两人都在水平桌面上放上一

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问题:

贝贝和晶晶在探究牛顿第二定律的过程中分别采用了以下方案:两人都在水平桌面上放上一端带有定滑轮的长木板,将相同质量的滑块放在木板上后,贝贝在滑块上用绳子连接重物A;晶晶则直接在滑块上施加竖直向下的拉力F.物体A受的重力和拉力F大小相同,如图1所示.不计物体与长木板间的摩擦,也不计绳的质量及绳与滑轮的摩擦,若m1运动的加速度为a1,m2运动的加速度为a2,那么:

(1)a1和a2的大小关系是______;

(2)在上面的探究过程中,若物体与长木板间的摩擦不能忽略,贝贝的方案中如何才能将实验误差减小,请你至少说出两条:①______,②______.

(3)若贝贝通过改变拉绳的重物A的质量进行多次实验,并根据记录的实验数据描出如图2所示的F-a图象,则该图象表明贝贝实验中可能存在的问题是______.

考点:牛顿第二定律
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(2011年湖南衡阳,2题)小明妈妈为他提供的一份午餐是:米饭、炒牛肉、馒头、鸡蛋汤。这份午餐中缺少下列那种营养素(   )

A.油脂

B.维生素

C.蛋白质

D.糖类

题型:问答题

公证文书的签署人员应写______

A.主任公证员
B.公证员
C.副主任公证员
D.助理公证员

题型:问答题

水污染源中,其中工业污染源的特点是()。

A.量大

B.含污染物多

C.成分复杂

D.处理比较容易

E.面广

题型:问答题

诱导性多能干细胞的出现基于哪些研究成果?

题型:问答题

Surprisingly enough, modern historians have rarely interested themselves in the history of the American South in the period before the South began to become self-consciously and distinctively " Southern"—the decades after 1815. Consequently, the cultural history of Britain’s North American empire in the seventeenth and eighteenth centuries has been written almost as if the Southern colonies had never existed. The American culture that emerged during the Colonial and Revolutionary eras has been depicted as having been simply an extension of New England Puritan culture.

However, Professor Davis has recently argued that the South stood apart from the rest of American society during this early period, following its own unique pattern of cultural development. The case for Southern distinctiveness rests_ upon two related premises: first, that the cultural similarities among the five Southern colonies were far more impressive than the differences, and second, that what made those colonies alike also made them different from the other colonies. The first, for which Davis offers an enormous amount of evidence, can be accepted without major recitations, the second is far more problematic.

What makes the second premise problematic is the use of the Puritan colonies as a basis for comparison. Quite properly,Davis decries the excessive influence ascribed by historians to the Puritans in the formation of American culture. Yet Davis inadvertently adds weight to such ascriptions by using the Puritans as the standard against which to assess the achievements and contributions of Southern colonials. Throughout, Davis focuses on the important and undeniable differences between the Southern and Puritan colonies in motives for and patterns of early settlement, in attitudes toward nature and Native Americans, and in the degree of receptivity to metropolitan cultural influences.

However, recent scholarship has ply suggested that those aspects of early New England culture that seem to have been most distinctly Puritan, such as the p religious orientation and the communal impulse, were not even typical of New England as a whole, but were largely confined to the two colonies of Massachusetts and Connecticut. Thus, what in contrast to the Puritan colonies appears to Davis to be peculiarly Southern-acquisitiveness. A p interest in polities and the law, and a tendency to cultivate metropolitan cultural models were not only more typically English than the cultural patterns exhibited by Puritan Massachusetts and Connecticut, but also almost certainly characteristic of most other early modern British colonies from Barbados north to Rhode Island and New Hampshire. Within the larger framework of American colonial life, then, not the Southern but the Puritan colonies appear to have been distinctive, and even they seem to have been rapidly assimilating to the dominant cultural patterns by the last Colonial period.

What do we learn about the cultural history of Britain’s North American empire from Paragraph 1()

A. The southern colonies had never existed before 17C

B. Historians nowadays ignore it for some reason unknown

C. The American culture during the Colonial era was actually New England Puritan Culture

D. People today think that history was not recorded by government

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