题目内容
某机械在每次匀速吊起货物时所能提供的功率P与所吊货物质量m的关系如图所示。现用该机械将30个货箱吊上离地12m高的平台,每个货箱的质量为5kg(忽略机械从平台返回地面和装箱的时间,g取10m/s2),所需最短时间约为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250050092585200.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250050092585200.png)
A.360s | B.720s | C.1440s | D.2400s |
B
试题分析:由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005009274631.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005009336695.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825005009368960.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
题目内容
A.360s | B.720s | C.1440s | D.2400s |