试题与答案

(1)如图1所示,ABC为一固定在竖直平面内的光滑轨道,BC段水平,AB段与BC

题型:问答题

题目:

(1)如图1所示,ABC为一固定在竖直平面内的光滑轨道,BC段水平,AB段与BC段平滑连接.质量为m1的小球从高位h处由静止开始沿轨道下滑,与静止在轨道BC段上质量为m2的小球发生碰撞,碰撞后两球的运动方向处于同一水平线上,且在碰撞过程中无机械能损失.求碰撞后小球m2的速度大小v2

(2)碰撞过程中的能量传递规律在屋里学中有着广泛的应用.为了探究这一规律,我们才用多球依次碰撞、碰撞前后速度在同一直线上、且无机械能损失的简化力学模型.如图2所示,在固定光滑水平轨道上,质量分别为m1、m2、m3…mn-1、mn…的若干个球沿直线静止相间排列,给第1个球初能Ek1,从而引起各球的依次碰撞.定义其中第n个球经过依次碰撞后获得的动能Ek与Ek1之比为第1个球对第n个球的动能传递系数k1n

a.求k1n

b.若m1=4m0,mk=m0,m0为确定的已知量.求m2为何值时,k1n值最大

答案:

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题型:完形填空
阅读下面短文,掌握其大意,然后从36-55各题所给的四个选项(A、B、C和D)中,选出最佳选项.
"Everything happens for the best." My mother said whenever I faced disappointment, "If you 36   one day something good will happen. And you'll realize that it wouldn't have happened if not for that previous   37 ."
Mother was right. After graduating from college I had decided to try for a job in   38  , then work my way up to   39  . I got   40  on the door of every station every time.
In one studio, a kind lady told me that big stations wouldn't   41  hiring an inexperienced person. "Go out in the sticks(边远地区) and find a   42  station that'll give you a chance." she said.
I thumbed(搭便车) home to Dixon, Illi.   43  there were no radio-announcing jobs in Dixon, my father said Montgomery Ward had opened a store and wanted a local   44  to manage   45  sports department. Since Dixon was where I had played high-school football, I  46  the post, but I wasn't hired.
My disappointment must have shown. "Everything happens for the best." Mom   47  me. I drove to Davenport, in Iowa. I   48  WOC Radio there. Peter Macarthur, the program director, told me they had already hired an announcer.
As I left his office, my frustration(挫折感)   49  over. I asked aloud. "How can a fellow get to be a sports announcer if he can't get a job in a radio station ?" I was waiting for the   50   when I heard Macarthur calling. "What was that you said about sports? Do you know anything about   51  ?" Then he stood me before a microphone and asked me to broadcast a(an)   52   game.
I remembered a game we had won. I did a 15-minute buildup to that play, and Peter told me I would   53  Saturday's game!
On my way home, I thought of my mother's words,   54  I have many times since, "If you … , one day something good will happen...."
I often wonder what my   55  might have been like if I'd gotten the job at Montgomery Ward.
小题1:
A.work hardB.are braveC.carry onD.are lucky
小题2:
A.problemsB.difficultyC.disappointmentD.unemployment
小题3:
A.sportsB.radioC.shopsD.clubs
小题4:
A.sports announcerB.sports starC.shop managerD.film maker
小题5:
A.turned awayB.turned downC.turned inD.turned off
小题6:
A.like B.decideC.standD.risk
小题7:
A.biggerB.smallC.localD.private
小题8:
A.IfB.WhileC.UnlessD.Until
小题9:
A.businessmanB.college studentC.athleteD.announcer
小题10:
A.his B.herC.theirD.its
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A.applied forB.acceptedC.consideredD.refused
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A.becameB.turnedC.wentD.boiled
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A.lift B.directorC.resultD.reply
小题16:
A.radioB.directingC.footballD.broadcasting
小题17:
A.live B.imaginaryC.excitingD.lively
小题18:
A.join inB.missC.broadcastD.organize
小题19:
A.asB.thenC.whenD.though
小题20:
A.dreamB.aimC.lifeD.failure
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