问题 多选题

平抛运动可以分解为水平和竖直两个方向的直线运动,在同一坐标系中作出这两个分运动的v-t图象,则(  )

A.图线2表示竖直分运动的v-t图线

B.这两个直线运动的合运动还是直线运动

C.水平方向的速度总大于竖直方向的速度

D.t1时刻水平方向的速度的与竖直方向的速度大小相等

答案

A、平抛运动的水平分运动为匀速直线运动,竖直分运动为自由落体运动,图线2表示匀加速直线运动,故表示竖直分运动,故A正确;

B、平抛运动的合运动为曲线运动,故B错误;

C、从图象可以看出,t1时刻后,水平方向的分速度就小于竖直方向的分速度,故C错误;

D、从图象可以看出,t1时刻水平方向的速度的与竖直方向的速度大小相等,故D正确;

故选AD.

完形填空

When I was thirteen, my family moved from Boston to Tucson, Arizona.  36  the move, my father  37  us in the living-room on a freezing January night. My sisters and I sat around the fire, not   38  that the universe would suddenly change its course. "In May, we're  39  to Arizona."

The words, so small, didn't seem  40  enough to hold my new life. But the world changed and I awoke on a train moving across the country. I watched the  41_  change from green trees to flat dusty plains to high mountains as I saw strange new plants that  42  mysteries(奥秘) yet to come. Finally, we arrived and  43  into our new home.

44  my older sisters were sad at the loss of friends, I   45  explored(探索) our new surroundings.

One afternoon, I was out exploring  46  and saw a new kind of cactus(仙人掌). I crouched (蹲) down for a closer look. "You'd better not  47  that."

I turned around to see an old woman

"Are you new to this neighborhood?" I explained that I was,  48 , new to the entire state.

"My name is Ina Thorne. Have you got used to life in the  49 ? It must be quite a _50  after living in Boston."

How could I explain how I  51  the desert? I couldn't seem to find the right words.

"It's vastness," she offered. “That vastness  52  you stand on the mountains overlooking the desert -- you can  53  how little you are in comparison with the world.     54  , you feel that the possibilities are limitless.”

That was it. That was the feeling I'd had ever since I'd first seen the mountains of my new home. Again, my  55  would change with just a few simple words.

"Would you like to come to my home tomorrow? Someone should teach you which plant you should and shouldn't touch."

36. A. During            B. Until               C. Upon                    D. Before   

37. A. gathered          B. warned            C. organized          D. comforted 

38. A. hoping              B. admitting         C. realizing            D. believing  

39. A. going                B. moving           C. driving                 D. flying    

40. A. good                 B. simple            C. big                       D. proper    

41. A. picture              B. ground            C. scene               D. area     

42. A. suggested                   B. solved            C. discovered         D. explained 

43. A. settled              B. walked           C. hurried              D. stepped

44. A. If                     B. After                    C. Once               D. While  

45. A. bitterly             B. easily                   C. proudly             D. eagerly   

46 A as well                B. as usual           C. right away         D. on time 

47. A. move                B. dig                         C. pull                  D. touch   

48. A. of course           B. in fact                    C. after all             D. at least  

49. A. desert               B. city                 C. state                  D. country 

50. A. luck                  B. doubt                C. shock                D. danger  

51. A. found               B. examined         C. watched            D. reached 

52. A. why                 B. when               C. how                         D. where   

53. A. prove                B. guess               C. sense                 D. expect   

54. A. However           B. Otherwise        C. Therefore              D. Meanwhile

55. A. idea                  B. life                        C. home                    D. family

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