-
题目： 单选题如图4-56所示，滑轮的转动惯量为JO，重物质量为m，拉力为F，绳与轮间不打滑。试求下述两种情况下，轮两边绳的拉力（）。
（1）重物以等速度v上升和下降 （2）重物以加速度a上升和下降
A在（1）中绳两边拉力不同
B在（2）中绳两边拉力相同
C在（2）中绳两边拉力不同
D在（1）、（2）中绳两边拉力均不确定
答案不对？请尝试站内搜索
推荐知识点:
- 诱导期是在规定的（）氧化条件下，汽油处于未被氧化的稳定状态所经历的时间。
- 风险管理的损前目标具体包括()。
- 一般立克次体发病1周，血清中即有补体结合抗体出现，以后逐渐上升，达到高峰后逐渐下降到一个较低的滴度，并可保持这一滴度几年不变。其达到高峰的时间是（）。
- 下列不属于焊剂的作用的是（）
- Women are also underrepresented in the administration and this is because there are so few women full professors. In 1985,Regent Beryl Milburn produced a report blasting（轰动）the University of Texas System administration for not encouraging women.The University was rated认为 among the lowest for the system.In a 1987 update ,Milburn commended the progress that was made and called for even more improvement. One of the positive results from her study was a System-wide program to inform women of available administrative jobs. College of Communication Associate Dean Patrica Witherspoon,said it is important that woman be flexible when it comesto relocating if they want to rise in the ranks. Although a woman may face a chilly climate on campus , many times in order for her to succeed , she must rise above the problems around her and concentrate on her work. Until women make up a greater percentage of the senior positions in the University and all academia,inequities will exist存在. "Women need to spend their energies(精力energy) and time doing scholarly activities that are important here at the University." Spirduso said. "If they do that will be successful in this system.If they spend their time in little groups mourning the sexual discrimination that they think exists here, they are wasting valuable study time." According to Spirduso,women need to （）. From this passage ,we know that（）. Which of the following statements is true?（） The title for this passage should be（）.
- 吸程过高需（）调整。
- 离心泵的基本结构有几部分组成？
- 何谓抽样误差？如何减小抽样误差？
- 重力式挡土墙墙背形式可分为（ ）。
- 公务员除了可以在公务员队伍内部交流外，还可以和哪些从事公务的人员交流？