您所在的当前位置：初中物理试题 >

速度与机械运动

> 下列事例中，增大摩擦的措施是 A.为了容易推动很重的木箱，在木箱下面垫上几根圆木 B.在机器的转动部分安装滚动轴承 C.在衣服的拉链上涂些蜡 D.在汽车轮胎上做成有凹凸不平的花纹

问题：

发布时间：2024-09-07

下列事例中，增大摩擦的措施是

A.为了容易推动很重的木箱，在木箱下面垫上几根圆木
B.在机器的转动部分安装滚动轴承
C.在衣服的拉链上涂些蜡
D.在汽车轮胎上做成有凹凸不平的花纹

参考答案：

提问用户：bn***MD1

可能感兴趣的题目：

1 撒哈拉以南的非洲地形 A.以平原为主 B.以高原为主 C.以盆地为主 D.以丘陵为主
2 已知 f(x)=sinx+ 3 cosx(x∈R) （1）求函数f（x）的最小正周期；（2）求函数f（x）的最大值，并指出此时x的值．
3 给出的程序框图如图，那么输出的数是（　　） A．2450 B．2550 C．5050 D．4900
4 某溶液中可能含有Na +、NH 4 +、Ba 2+、SO 4 2-、I -、S 2-．分别取样：①用pH计测试，溶液显弱酸性；②加氯水和淀粉无明显现象．为确定该溶液的组成，还需检验的离子是（　　） A．Na+ B．SO42- C．Ba2+ D．NH4+
5 ⑴小球滑到最低点 B时，小球速度 v的大小； ⑵小球刚到达最低点 B时，轨道对小球支持力 F N的大小； ⑶小球通过光滑的水平面 BC滑上固定曲面，恰达最高点 D， D到地面的高度为 h（已知 h＜ R），则小球在曲面上克服摩擦力所做的功 Wf.
6 完形填空。 " Hi! John. "Mary ran towards me with a rare bright smile on her face, saying, "I"m going to have a 1 performance tonight. Ihope you"ll come. Here is the 2 ". She left in a hurry,disappearing in the crowds of people 3 . "Is that true?" I asked myself. She was a quite 4 girl.I had never seen her making up or wearing attractive clothes,for she did not know how to 5 indeed. I arrived at the 6 with the ticket, and found my seat.Her performance was the seventh one. I knew I would 7 from a hard time before her turn, for I had no 8 of art,but her performance was 9 watching, no matter how longI would wait. Time went slowly. I 25 with myself not to fall asleep. "Let" s welcome the next exciting dance-Latin!" 11 filled the hall at once. I opened my eyes as large as possible, 12 to loseanything. Wearing a golden and shining skirt, Mary appearedon the stage. Dancing with a charming smile, she was fully 13 in the Latin music. At this moment, she looked like apretty butterfly 14 on the splendid stage. After all the performance 15 , I waited for her at thegate. "Hi!" She stood in front of me with a bag and her crystal(水晶)high-heeled shoes in her hands, and 16 as she usedto be, but the making-up still could be seen. "How do you feel?" There was not a little bit tired 17 on her face." 18 !" I answered. "Thank you! I knew it would be. " She could not 19 her excitement, laughing like a child. Looking at the shiningcrystal high-heeled shoes in the wonderful starry night, 20 that every girl has a pair of special shoes which are likethe crystal shoes of Cinderella (灰姑娘). ( )1. A. instrument ( )2. A. address ( )3. A. quickly ( )4. A. lovely ( )5. A. cover up ( )6. A. hall ( )7. A. relieve ( )8. A. interest ( )9. A. proper ( )10. A. struggled ( )11. A. Appreciation ( )12. A. failing ( )13. A. absorbed ( )14. A. singing ( )15. A. stopped ( )16. A. talked ( )17. A. appearance ( )18. A. Sorry ( )19. A. hide ( )20. A. doubted B. dance B. number B. completely B. popular B. turn off B. party B. escape B. ability B. worth B. knocked B. Attention B. fearing B. swallowed B. flying B. paused B. dressed B. excitement B. Congratulations B. prevent B. realized C. music C. ticket C. quietly C. confident C. dress up C. theatre C. relax C. sense C. good C. supported C. Expectation C. forgetting C. interested C. skipping C. ended C. laughed C. expression C. Far from C. remove C. wondered D. opera D. invitation D. excitedly D. ordinary D. take in D. school D. suffer D. touch D. happy D. shouted D. Applause D. regretting D. surrounded D. staying D. succeeded D. looked D. exhibition D. Fantastic D. abandon D. suggested
7 该图表示某种农产品生产和销售的一般模式，读图完成1—3题：小题1:据图知：阶段Ⅰ鲜花和蔬菜产区的主要区位因素是 A．地形平坦 B．气候优越 C．距城区近 D．水源充足小题2:阶段Ⅱ鲜花和蔬菜产区的区位变化的主要原因是 A．城市用地规模的扩大 B．城市人口的增加 C．交通运输的发展 D．城市居民收入的提高小题3:若甲是北京，乙为广州，则阶段Ⅱ运量最大的季节是 A．春季 B．夏季 C．秋季 D．冬季
8 地理信息技术已为人类广泛应用，下列用法最合理的是 A．利用GPS来监测森林火情 B．利用GIS进行土地利用现状调查 C．利用RS设计旅游路线 D．利用GPS测量珠峰高度
9 沙尘暴天气会严重影响交通．有一辆卡车以54 km/h的速度匀速行驶，司机突然模糊看到正前方十字路口一个老人跌倒(若没有人扶起他)，该司机刹车的反应时间为0.6 s，刹车后卡车匀减速前进，最后停在老人前1.5 m处，避免了一场事故．已知刹车过程中卡车加速度大小为5 m/s 2，则 A．司机发现情况后，卡车经过3 s停下 B．司机发现情况时，卡车与该老人的距离为33 m C．从司机发现情况到停下来过程中卡车的平均速度为11 m/s D．若卡车的初速度为72 km/h，其他条件都不变，则卡车将撞到老人
10 Eric’s never seen a three-D movie at the cinema，_______? A.hasn’t he B.has he C.isn’t he D.is he