问题
不定项选择
如图所示，矩形线框自某一高度自由下落，然后进入匀强磁场中，线框刚要进入匀强磁场时的动能Ek1，线框刚好穿过磁场时的动能为Ek2，线框穿过磁场过程中产生的焦耳热为Q，克服安培力做功为W1，重力对线框做功为W2，则下列关系中正确的是
A. Q=W1
B. Q=Ek2-Ek1
C. Q=W2=W1
D. W2=W1+(Ek2-Ek1)
答案
AD
搜题请搜索小程序“爱下问搜题”
如图所示，矩形线框自某一高度自由下落，然后进入匀强磁场中，线框刚要进入匀强磁场时的动能Ek1，线框刚好穿过磁场时的动能为Ek2，线框穿过磁场过程中产生的焦耳热为Q，克服安培力做功为W1，重力对线框做功为W2，则下列关系中正确的是
A. Q=W1
B. Q=Ek2-Ek1
C. Q=W2=W1
D. W2=W1+(Ek2-Ek1)
AD
| 完形填空。 | |||
| A young student was one day taking a walk with a professor, who was commonly 1 the students' friend. As they went 2 , they saw lying in the path a pair of old shoes, which they supposed to 3 a poor man who was employed in a field 4 . The student turned to the professor, saying,"Let us play the man 5 : we will hide his shoes, and 6 ourselves behind those bushes, and wait to see his 7 when he cannot find them. " "My young friend," answered the professor, "we should never 8 ourselves at the 9 of the poor. But you are 10 , and may give yourself a much greater 11 by means of the poor man. Put a coin into each shoe, and then we will hide ourselves and 12 how the discovery affects him. " The student did so, and they both placed themselves behind the bushes. The poor man soon finished his work and 13 the field to the path 14 he had left his coat and shoes. While 15 his coat he slipped his foot into one of his shoes; but feeling something 16 , he stooped down (弯下腰) to feel 17 it was, and found the coin. Astonishment and wonder were seen upon his countenance(面部表情). He then looked around him on all sides, but no person was to be seen. He now put the money into his pocket, and proceeded to put on the other shoe; but his surprise was 18 on finding the other coin. He fell upon his knees, looked up to heaven and uttered aloud a fervent (热烈的) thanksgiving, in which he 19 his wife, sick and helpless, and his children without brea d. The student stood there 20 affected, and his eyes filled with tears. | |||
| ( )1. A. held ( )2. A. along ( )3. A. get to ( )4. A. close by ( )5. A. a game ( )6. A. hide ( )7. A. pleasure ( )8. A. make ( )9. A. money ( )10. A. poor ( )11. A. pleasure ( )12. A. notice ( )13. A. came about ( )14. A. where ( )15. A. wearing ( )16. A. soft ( )17. A. what ( )18. A. increased ( )19. A. spoke of ( )20. A. heavily | B. kept B. on B. stick to B. far B. a trick B. have B. sorrow B. treat B. expense B. kind B. money B. watch B. came across B. on which B. dressing B. terrible B. how B. put B. told of B. slightly | C. named C. over C. belong to C. faraway C. a joke C. let C. disappointment C. amuse C. value C. honest C. thought C. observe C. came into C. there C. putting on C. strange C. whether C. doubled C. talked about C. easily | D. called D. back D. object to D. near D. a word D. make D. anxiety D. laugh D. pay D. rich D. good D. see D. came by D. which D. changing D. hard D. why D. reduced D. said about D. deeply |