您所在的当前位置：初中物理试题 >

机械效率

> 体积相等的铁球和铅球从三楼掉到一楼，则 A.在三楼，铁球和铅球的势能相等，落到一楼时动能也相等 B.在三楼，铅球的势能大，落到一楼时动能也大 C.在三楼，铅球的势能大，落到一楼时铁球的动能大 D.在三楼，铁球的势能大，落到一楼时铅球的动能大

问题：

发布时间：2024-09-13

体积相等的铁球和铅球从三楼掉到一楼，则

A.在三楼，铁球和铅球的势能相等，落到一楼时动能也相等
B.在三楼，铅球的势能大，落到一楼时动能也大
C.在三楼，铅球的势能大，落到一楼时铁球的动能大
D.在三楼，铁球的势能大，落到一楼时铅球的动能大

参考答案：

提问用户：PA***3En

可能感兴趣的题目：

1 有10000吨花岗岩板材，从泉州出口到日本，最适合的交通方式是 A.海上运输 B.铁路运输 C.公路运输 D.航空运输
2 哲学上讲的“一分为二”与 “合二为一”，体现了事物矛盾双方（） A．在一定条件下相互依存 B．在一定条件下相互转化 C．既对立又统一的关系 D．既相互区别又相互排斥
3 如图所示，木块A的右侧为光滑曲面，且下端极薄．其质量为1.0kg，静止于光滑的水平面上，一个质量也为1.0kg的小球B以5.0m/s的速度从右向左运动冲上A的曲面，与A发生相互作用．B球与A曲面相互作用结束后，B球的速度是（　　） A．0 B．1.0m/s C．0.71m/s D．0.50m/s
4 Observer 2007-03-28 13:54 Nothing could be more shameful for McDonald’s and KFC. They are violating labour’s rights. The government must immediately bring the guilty to justice. A stricter government inspection system must be enforced to protect the workers. Nathan 2007-03-28 21:39 It is known that McDonald’s and KFC and other fast-food restaurants pay the lowest wage they possibly can to get their employees. I think it’s kind of funny that these two restaurants have not yet set up unions. It is also known that they also take every possible measure e(legal, and sometimes illegal) to prevent their employees from forming or joining unions. I think it is high time that government enforced the law that they have made. Cushman 2007-03-28 22:32 The deepest reason is that China has a large population. If you complain that the pay is very low, the boss will tell you that can go to other places and that there are a lot of people waiting for the job. Today finding a job is not very easy, so you don’t have many choices, and you have to face the reality. Chip 2007-03-29 20:33 If wages were too low, people wouldn’t work for them, but they do, so it proves the wages are reasonable. Sure, they could raise the wages, but why should they? The workers are still working, still willing to show up on time, and it keeps costs lower. Were they to raise wages, they would have to FIRE more workers, and the price of burgers would go up. Then people wouldn’t buy them, then McDonald’s would once again FIRE more workers because of a reduced demand, and you’d be back in the same boat, just with less people working. 小题1:What are they debating about? A．McDonald’s and KFC pay too low a salary to their employees. B．Setting up a social security system. C．Fast-food restaurants have no rights to fire workers. D．McDonald’s and KFC will be punished for their behaviour. 小题2:According to Chip, it is____for McDonald’s and KFC to give employees a low salary. A．unacceptable B．shameful C．acceptable D．illegal 小题3: In the opinion of Cushman, the key to the problem is that____. A．the social security net has not been set up B．China has too large a population C．the government has not taken stronger steps to protect workers D．the unions have not played an important part to raise the wages. 小题4: The underlined word “they” in Nathan’s words refers to____. A．the employees B．governments C．all the restaurants D．fast-food restaurants
5 今年是和平共处五项原则提出60周年。坚持和平共处五项原则，是我国处理对外关系的基本准则。对这一基本准则理解正确的是 ①我国从中国人民和世界人民的根本利益出发，根据事情本身的是非曲直决定自己的立场和政策 ②我国坚持“与邻为善、以邻为伴”方针，积极发展同周边国家的睦邻友好关系 ③我国是维护世界和平与稳定的积极因素和主导力量 ④我国重视改善和发展同发达国家的关系，主张国与国之间互相尊重，扩大互利合作 A．①② B．②③ C．②④ D．①④
6 Mike was ___ praised for his handwriting by the teacher in class. A．high B．highly C．deep D．seriously
7 下图人物在2000年的世纪之交曾被西方主要媒体评为“千年风云人物”；他离开我们已有一百多年，但其学说仍然在深刻地影响着人类的生活。下列不属于他的活动的是 [ ] A．创建“第一国际” B．创办《新莱茵报》 C．创立马克思主义 D．研究垄断组织的出现
8 被称为现代工业的“血液”，在我国是第二大能源的是 A.煤 B.石油 C.核 D.水
9 一质量为 m的小球以速度水平抛出，经时间 t落地，（不计空气阻力，重力加速度为g）求：（1）此过程重力做的功；（2）此过程中重力做功的平均功率；（3）小球落地时重力做功的瞬时功率。
10 德国鲁尔区丰富的煤炭资源使它成为世界最著名的工业区之一；山西省是我国的煤炭生产大省，但尚未成为经济强省。据此完成11-13题。小题1:导致鲁尔区衰落的原因中，不属于受世界工业发展形势影响的是（） A．生产结构单一 B．煤炭的能源地位下降 C．钢铁生产过剩 D．新技术革命的冲击小题2:与鲁尔区相比，山西省发展经济的有利条件是（） A．水源丰富 B．科技发达 C．劳动力廉价 D．交通便利小题3:山西省由能源大省转变为经济强省的发展策略应该有（） ①大力增加煤炭工业的比重 ②调整产业结构，积极发展第三产业 ③增加科技投入，走可持续发展之路 ④治理水土流失，改善和保护生态环境 A．①②③ B．②③④ C．①③④ D．①②④