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问题 填空题

如图所示，为“探究加速度与力、质量的关系”实验装置图。图中A为小车，B为砝码及砝码盘，C为一端带有定滑轮的长木板，小车通过纸带与电火花打点计时器相连，计时器接50Hz交流电。小车A的质量为m1，砝码及砝码盘B的质量为m2。

小题1:下列说法正确的是       。

A．每次改变小车质量时，应重新平衡摩擦力

B．实验时应先释放小车后接通电源

C．本实验m2应远大于m1

D．在用图象探究加速度与质量关系时，应作a-图象小题2:实验时，某同学由于疏忽，遗漏了平衡摩擦力这一步骤，他测

量得到的a- F图像，可能是图中的图线       。(选填“甲”、

“ 乙”、“ 丙”)

小题3:如图所示为某次实验得到的纸带，纸带中相邻计数点间的距离已标出，相邻计数点间还有四个点没有画出。由此可求得小车的加速度大小      m/s2。（结果保留二位有效数字）

答案

小题1:D

小题2:丙

小题3:0.49或0.50

1. 平衡摩擦力是根据，与质量无关，所以改变小车质量时，不需要重新平衡摩擦力A错。实验时应先接通电源后释放小车，这样才能让打点计时器在工作稳定状态下打出点迹，B错。m2应远小于m1小车受到的拉力才近似等于砝码及砝码盘的重力，C错。若做-图像，不能确定是几次函数关系，而a-图象，可明确看出线性关系，D对。

2.若存在摩擦力，当F较小时，加速仍为0，所以丙图对。

3.根据得，。

单项选择题 A1/A2型题

钛合金铸造时必须保证良好的真空状态的原因是（）

A.纯钛的结构在常温下呈α相

B.纯钛的密度高

C.纯钛的弹性模量大

D.纯钛的熔点高

E.纯钛的化学性能稳定
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完形填空

Granny Sarya lived outside Moscow． Her only son  16  to Afghanistan(阿富汗) and was killed in action there．Soon after that, her husband lost his job． The old man was always   17  food and clothes．And on a winter night he went out alone when Sarya was asleep． The next morning he was   18  dead in a cold lake． And his worn-out coat was   19  in a tree not far away． Sarya was so   20  that she nearly took her own life．
Things got worse and worse after that． She always lived in hunger and cold． She had hoped that the government(政府) could help her but she    21 ．
It was a cold windy night． The old woman couldn't   22  asleep at all． She had to get up． She decided to write a letter to God（神）, asking for  23 ． She wished God to give her 100 rubles (卢布), so she could buy some food for herself． When she  24  writing it, she found she had no  25 ． She had to put the  26  at a crossing．   27  the next morning a policeman found the letter． He read it to his comrades．They were all so   28  that they gathered some rubles and sent them to the poor old woman．
At first Granny Sarya was happy． But after she   29  the money, she became   30  and said, “I'm told that all things that are touched by the policeman will be only a half left!”
小题1:
A．sentB．ran awayC．was sent D．escaped
小题2:
A．worried aboutB．pleased withC．thinking aboutD．hearing of
小题3:
A．knownB．foundC．toldD．fallen
小题4:
A．putB．hangedC．shownD．hung
小题5:
A．sadB．happyC．tiredD．clever
小题6:
A．succeededB．failedC．wonD．lost
小题7:
A．goB．fallC．getD．help
小题8:
A．coatsB．foodC．housesD．help
小题9:
A．endedB．startedC．finishedD．enjoyed
小题10:
A．stampB．moneyC．penD．paper
小题11:
A．foodB．letterC．coatD．rubles
小题12:
A．BadlyB．CarefullyC．LuckilyD．Wonderfully
小题13:
A．excitedB．movedC．amazedD．surprised
小题14:
A．sawB．receivedC．gaveD．counted
小题15:
A．angryB．thankfulC．helpfulD．worried
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