问题 计算题

如图所示,顶端粗糙的小车,放在光滑的水平地面上,具有一定速度的小木块由小车左端滑上小车,当木块与小车相对静止时,木块相对小车的位移为d,小车相对于地面的位移为x,求整个过程中动能的变化量。

答案

解:滑动摩擦力对木块做的功为W=-f(d+x) ①

由动能定理可知木块的动能增量为△Ek木=-f(d+x) ②

滑动摩擦力对小车做的功为W=fx ③

同理,小车动能增量为△Ek车=fx ④

把②④两式相加得动能的变化△Ek木+△Ek车=-fd ⑤

完形填空
Monty Roberts often let me use his house to hold fund-raising events to raise money for young people in need.
The last time I was there he   36  me to a group of people by saying, “I want tell you   37  I let Jack use my house. It   38  a story about a young man. When he was a high school student, he was asked to write a paper about his   39 .”
“That night be wrote a seven-page paper   40  his goal of someday owning a horse ranch (大牧场). He wrote about his dream in great   41  and he even drew a picture of a 200-acre ranch, showing the   42  of all the buildings, the stables(马厩)and the track. Then he drew a detailed plan for a 4,000-square-foot house that would   43  on a 200-acre ranch.”
“When he received his paper, he found that there was a big red ‘F’ on the front page with a note   44 , ‘see me after class.’”
“The boy went to see the teacher after class and asked, ‘Why did I receive an F?’”
“The teacher said, ‘This is a(an)  45  dream for a young boy like you. If you __46  this paper with a more realistic goal, I will reconsider your   47  .’”
“Finally, after a week, the boy handed in the same paper, making no   48 . He stated, ‘You can   49  the F and I’ll keep my dream.’”
“I told you this story because you are sitting in my 4,000-square-foot   50  in the middle of my 200-acre ranch. I still have that school   51  .”
He added, “That   52  teacher came to my ranch. Before leaving, he said, ‘During those years I   53  a lot of kids’ dreams.   54 , you didn’t give up yours.
Don’t let anyone steal your dream. Follow your   55 , no matter what.
小题1:
A.warnedB.informedC.helpedD.introduced
小题2:
A.whyB.whenC.howD.where
小题3:
A.breaks away fromB.gets along with
C.goes back toD.is occupied with
小题4:
A.feelingB.dreamC.difficultyD.contribution
小题5:
A.expectingB.drawingC.imaginingD.describing
小题6:
A.strengthB.detailC.surpriseD.courage
小题7:
A.ownerB.constructionC.locationsD.prices
小题8:
A.sitB.coverC.riseD.remain
小题9:
A.writingB.expressingC.suggestingD.reading
小题10:
A.unrealisticB.wonderfulC.fantasticD.disappointing
小题11:
A.exchangeB.checkC.rewriteD.treat
小题12:
A.goalB.gradeC.futureD.behavior
小题13:
A.sensesB.changesC.commentsD.excuses
小题14:
A.keepB.followC.continueD.choose
小题15:
A.fieldB.ranchC.officeD.house
小题16:
A.buildingB.addressC.storyD.paper
小题17:
A.sameB.kindC.singleD.famous
小题18:
A.testedB.askedC.stoleD.missed
小题19:
A.ThereforeB.FortunatelyC.SurprisinglyD.Generally
小题20:
A.adviceB.heartC.trendD.statement
完形填空
In some cities, workaholism(废寝忘食工作)is so common that people don’t consider it unusual. They accept the lifestyle as   26 .  Government
workers in Washington, D. C.,   27 , frequently work sixty to seventy hours a week. They don’t do this because they have to; they do it because they   28  to. Workaholism can be a   29  problem. Because true workaholics would rather work than do anything else, they   30  have no idea of how to relax; that is, they might not   31  movies, sports, or other types of entertainment. Most of all, they   32  to sit and do nothing. The lives of workaholics are usually stressful, and this tension(紧张)and worry can cause   33  problems such as heart attacks and stomach diseases.    34  , typical workaholics don’t pay much attention to their families. Their marriages may end in   35  as they spend little time with their families.
Is workaholism   36  dangerous? Perhaps not. There are, certainly, people who work   37  under stress. Some studies show that many workaholics have great energy and interest in work. They feel   38  is so pleasurable that they are actually very happy. For most workaholics, work and entertainment are the same thing. Their jobs   39  them with a challenge; this keeps them busy and creative.
  40  do workaholics enjoy their jobs so much? There are several  41  to work. Of course, it provides people with paychecks, and this is important. But it offer  42  financial security. It provides people with self-confidence; they have a feeling of satisfaction   43  they have produced a challenging piece of work and are able to say “I   44  it”. Psychologists claim that their work gives people an identity(自身价值). After they take part in work, they    45  a sense of self and individualism.
小题1:
A.strangeB.boring C.pleasant D.normal
小题2:
A.for example B.on the other handC.what’s more D.after all
小题3:
A.agreeB.promise C.dare D.want
小题4:
A.slightB.serious C.obvious D.difficult
小题5:
A.stillB.probably C.certainly D.mostly
小题6:
A.afford B.enjoy C.watch D.allow
小题7:
A.dream B.decideC.intend D.hate
小题8:
A.physical B.cultural C.social D.mental
小题9:
A.Therefore B.However C.AnywayD.Besides
小题10:
A.happiness B.silence C.failure D.surprise
小题11:
A.sometimes B.always C.seldom D.hardly
小题12:
A.sadly B.differently C.efficiently D.slowly
小题13:
A.study B.family C.life D.work
小题14:
A.equip B.pack C.provide D.fill
小题15:
A.When B.Why C.How D.Where
小题16:
A.factors B.advantages C.steps D.ways
小题17:
A.no more B.more or lessC.no more than D.more than
小题18:
A.when B.before C.unless D.until
小题19:
A.valued B.failed C.caught D.made
小题20:
A.give B.lose C.get D.need