问题 填空题

利用图示装置可以做力学中的许多实验.

(1)以下说法正确的是 .

A.利用此装置“研究匀变速直线运动”时,必须设法消除小车和木板间的摩擦阻力的影响

B.利用此装置探究“小车的加速度与质量的关系”并用图象法处理数据时,如果画出的a-M关系图象不是直线,就可确定加速度与质量成反比

C.利用此装置探究“功与速度变化的关系”实验时,应将木板带打点计时器的一端适当垫高,这样做的目的是利用小车重力沿斜面分力补偿小车运动中所受阻力的影响

(2)小华在利用此装置“探究加速度a与力F的关系”时,因为不断增加所挂钩码的个数,导致钧码的质量远远大于小车的质量,则小车加速度a的值随钧码个数的增加将趋近于 的值.

答案

(1)A、此装置可以用来研究匀变速直线运动,但不需要平衡摩擦力,所以A不准确.

B、曲线的种类有双曲线、抛物线、三角函数曲线等多种,所以若a-M图象是曲线,不能断定曲线是双曲线,即不能断定加速度与质量成反比,应画出a-

1
M
图象,故B错误.

C、探究“功与速度变化的关系”实验时,需要平衡摩擦力,方法是将木板带打点计时器的一端适当垫高,这样做的目的是利用小车重力沿斜面分力补偿小车运动中所受阻力的影响,从而小车受到的合力即为绳子的拉力,故C正确.

(2)设小车质量为m,钩码质量为M,则对小车有Mg-F=Ma   ①

对钩码有F-μmg=ma  ②

联立①②解得a=

M-μm
M+m
g

将上式变形为a=

1-
μm
M
1+
m
M
g,可见当M>>m时,加速度a趋近于g.

故答案为(1)C

        (2)g

完形填空

      完形填空(共20小题,每小题1.5分,满分30分)

Once there was a very brilliant, creative and educated man. He gained much   36   while traveling throughout the world. Unfortunately he lost his legs and left arm in a tragic accident, leaving only a finger and thumb on his right hand. He became so   37  that he was afraid he would spend his life   38   and would no longer be able to use his life in a(n)   39  way.

One day, he remembered how he had always loved getting   40  . He realized that he still had partial   41  of his right hand and could write with   42  . Then, he had an idea. “Why not write to other people who need encouragement?”

He   43   where he could find those who could be encouraged if they read his letters. He thought of people in   44 . Many of them had hope of regaining their   45  . Others would keep feeling depressed and remain put away for the rest of their lives. He decided that he must try to   46  them. So he wrote to a prison ministry about sending letters to the prisoners. The prison minister replied that writing to the prisoners would be   47  . However, it would be against prison rules for the prisoners to write back.

48   with the intention, the man began sending   49   messages of God’s love, hope, strength, and encouragement. He wrote twice a week, testing his strength and ability to the   50 . He poured his heart and soul into his words,   51   his experience, sense of humor, optimism, and faith.

It was difficult to write those letters, especially without hope of any   52  . Frequently, he felt discouraged, wondering if anyone   53   read his letters. However, this was his   54   chance,so he determined to continue.

At last, he received a letter from the prison officer, which said, “Please write on the best paper you can afford. Your letters are passed from cell (牢房) to cell until they almost fall to   55  !”

We all have unique experiences, abilities and talents. We can discover ways to reach others in need of encouragement and strength.

36. A. wealth             B. faith      C. experience  D. confidence

37. A. depressed            B. embarrassed       C. ashamed       D. thrilled

38. A. writing        B. suffering       C. weeping      D. wandering

39. A. abnormal            B. regular          C. comfortable       D. meaningful

40. A. presents        B. e-mails          C. letters    D. prizes

41. A. sense              B. strength         C. shape        D. function

42. A. affection            B. caution          C. difficulty       D. confidence

43. A. estimated       B. doubted         C. assumed         D. wondered

44. A. hospitals            B. churches        C. prisons        D. charities

45. A. families            B. letters     C. freedom         D. conscience

46. A. release             B. reach         C. defend          D. know

47. A. acceptable      B. reasonable  C. prohibited       D. considered

48. A. Faced             B. Filled         C. Satisfied    D. Impressed

49. A. holy              B. daily          C. one-way     D. round-way

50. A. point              B. worst         C. degree       D. limit

51. A. sharing             B. learning        C. gaining       D. enriching

52. A. success             B. reply          C. help           D. progress

53. A. curiously            B. patiently        C. carefully       D. actually

54. A. only              B. better           C. extra         D. lost

55. A. ruin               B. pieces     C. the ground  D. the bottom

单项选择题