如图所示,一边长L= 0.2m,质量m1=0.5kg,电阻R= 0.1Ω的正方形

题型:计算题

问题:

如图所示,一边长L= 0.2m,质量m1=0.5kg,电阻R= 0.1Ω的正方形导体线框abcd,与一质量为m2=2kg的物块通过轻质细线跨过两定滑轮相连。起初ad边距磁场下边界为d1=0.8m,磁感应强度B=2.5T,磁场宽度d2=0.3m,物块放在倾角θ=53°的斜面上,物块与斜面间的动摩擦因数μ=0.5。现将物块由静止释放,经一段时间后发现当ad边从磁场上边缘穿出时,线框恰好做匀速运动。(g取10m/s2,sin53°=0.8,cos53°= 0.6)求:  

(1)线框ad边从磁场上边缘穿出时速度的大小?

(2)线框刚刚全部进入磁场时动能的大小?  

(3)整个运动过程线框产生的焦耳热为多少?

考点:动能定理共点力的平衡能量转化与守恒定律
题型:计算题

长翅红眼雄蝇与长翅白眼雌蝇交配,产下一只染色体组成为XXY的残翅白眼雄蝇。已知翅长、眼色基因分别位于常染色体(A—长翅,a—残翅)和X染色体(B—红眼,b—白眼)上,在没有基因突变的情况下,下列分析正确的是[ ]

A.该染色体组成为XXY的白眼雄蝇体细胞中含有3个染色体组

B.产生该白眼雄蝇可能是父本雄蝇减数第一次分裂出错,XY同源染色体没有分离,产生异常的精子XY与正常卵细胞结合

C.产生该白眼雄蝇可能是母本雌蝇仅减数第一次分裂出错,此时于亲代雌蝇参与受精的卵细胞一起产生的三个极体基因型可能为AXb,AXb,a

D.产生该白眼雄蝇可能是母本雌蝇仅减数第二次分裂出错,此时于亲代雌蝇参与受精的卵细胞一起产生的三个极体基因型可能为AXb,AXb,a

题型:计算题

重力式方块码头为墩式建筑物时,方块安装以墩为单位,逐墩安装,每个墩()逐层安装。

A.由一边的一角开始

B.由一端向另一端安装

C.由中间向四周安装

D.先安外侧,后安内侧

题型:计算题

阅读理解。

     Who are the elders in your family? The most common answer is that they are your parents, grandparents,

uncles, aunts, and elder cousins--in a word, any relative who is older than you. But that doesn't really answer

the question, does it? In a normal family, there is a big difference between being elderly and being an elder.

     Elders are the storytellers, the cooks, the historians, the authorities, the knitters, and the workhorses. They

are the people we respect and turn to for answers or help when we are in trouble, because of their many years

of life experience. Most of all, they are the people who raised you and your loved ones and helped you growing

into the people you are. For many years, they carried the burden of caring for your family and leading it to

better times. Now it's your turn to dote on them. Ensuring the welfare of your elders should come as naturally

to us as raising our children.

     Unfortunately, too many people take their parents' and grandparents' ability to care for them for granted.

And in a country where so many of us live hundreds of miles from our families, looking after loved ones can

be difficult. Even so, you should make sure your loved ones are taken care of no matter where they live, and

try to look after the seniors living alone in your neighbor, too. Taking responsibility for the elders in our society

in an important thing that all citizens should do.

1. According to the author, elders are those who _____.

A. are much older than us

B. bring us up by working hard

C. give us money and food

D. have many interesting stories

2. Which of the following opinions doesn't the author agree with?

A. naturally that the elders should take care of themselves

B. It's our duty to take care of the elders when they are old

C. We should take care of the elders even if a long distance separates us from them

D. Looking after the elders is as important as raising our children

3. In which of the following columns would you most probably read this passage?

A. Education

B. Parenting

C. Society

D. Family

4. The passage was written to _____.

A. explain what elders are like

B. criticize those people who don't respect elders

C. Explain why we should love elders

D. Call on people to respect and love elders

题型:计算题

核心处理器与流量计之间的最长电缆限制是()米。

A、5

B、10

C、100

D、300

题型:计算题

等额本金还款法的特点有( )。

A.贷款期内每月等额偿还本金

B.贷款期内还款额度逐月递增

C.贷款期内偿还的利息逐月递增

D.贷款期内偿还的本金逐月递增

E.贷款期内每月贷款余额以定额逐渐减少

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