问题
选择题
在验证“机械能守恒定律”的实验中，下列物理量中需要直接测量的是：（ ）
A．重锤的质量；
B．重锤下落的高度；
C．重力加速度；
D．重锤下落某一高度所对应的瞬时速度。
答案
答案：B
重锤的质量不需要测量，A错；重力加速度不需要测量，C错；下落到某一高度需要用匀变速直线运动公式去求，不是直接测量的量，D错；
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在验证“机械能守恒定律”的实验中，下列物理量中需要直接测量的是：（ ）
A．重锤的质量；
B．重锤下落的高度；
C．重力加速度；
D．重锤下落某一高度所对应的瞬时速度。
答案：B
重锤的质量不需要测量，A错；重力加速度不需要测量，C错；下落到某一高度需要用匀变速直线运动公式去求，不是直接测量的量，D错；
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| She turned up at the doorstep of my house in Cornwall. Noy way could I have 1 .Maybe someone had kicked her 2 their car the night before ."No 3 for her any more with the baby coming." "We never really wanted her, but what could we have done?She was a 4 ." People find all sorts of excuses for 5 an animal. I called her Goldie. If I had 6 what was going to happen I would have given her a more creative name. She was so unsettled during those 7 few days. She hardly ate anything and had such an air of 8 about her. There was 9 I could do to make her happy, it seemed. Heaven knows what had happened to her at her 10 owner's. But 11 at the end of the first week she calmed down. Always by my side. 12 we were out on one of our long walks or sitting by the fire. That's why it was such a 13 when she pulled away from me one day when we were out for a walk. We were walking a long way from home, when she started 14 and getting very restless. Eventually I couldn't hold her any longer and she 15 down the road towards a farmhouse in the distance as fast as she could. By the time I 16 the farm I was very tired and upset with Goldie. But when I saw her licking (舔) the four puppies(幼犬)I started to feel 17 towards them. The woman at the door said, "I took her for a walk one day, 18 the puppies were born, and she just disappeared." "She must have tried to come back to them and got lost," 19 a boy from behind her. I must admit I do miss Goldie, but I've got Nugget now, and she looks just like her 20 .And I've learnt a good lesson:not to judge people. | |||
| ( )1. A. sent her away ( )2. A. beyond ( )3. A. seat ( )4. A. gift ( )5. A. taking ( )6. A. thought ( )7. A. first ( )8. A. darkness ( )9. A. something ( )10. A. familiar ( )11. A. eventually ( )12. A. while ( )13. A. joy ( )14. A. barking ( )15. A. walked away ( )16. A. landed ( )17. A. anxiety ( )18. A. every time ( )19. A. added ( )20. A. aunt | B. sold it out B. out of B. interest B. reminder B. protecting B. known B. last B. happiness B. anything B. previous B. unwillingly B. as B. shock B. eating B. fell over B. reached B. respect B. before long B. whispered B. sister | C. picked it up C. from C. chance C. surprise C. abandoning C. hoped C. usual C. sadness C. everything C. cruel C. unexpectedly C. either C. sight C. crying C. dropped out C. left C. sympathy C. once in a while C. called C. mother | D. turned it down D. within D. space D. bargain D. removing D. imagined D. special D. eagerness D. nothing D. troublesome D. probably D. whether D. trouble D. running D. raced off D. found D. pleasure D. soon after D. warned D. child |