【单选题】Which of the following is the correct order of the events.? a. The Spanish made Panama its colony. b. An armed rebellion (起义)against Spain took place in Central America. c. Panama joined Colombia in f...
【单选题】Which of the following is the correct order of the events? a. The Spanish made Panama its colony. b. An armed rebellion(起义)against Spain took place in Central America. c. Panama joined Colombia in fig...
【简答题】质量 m = 1.1 kg 的匀质圆盘,可以绕通过其中心且垂直盘面的水平光滑固定轴转动,对轴的转动惯量 J = mr 2 /2 ( r 为盘的半径 ) .圆盘边缘绕有绳子,绳子下端挂一质量 m 1 = 1.0 kg 的物体,如题图所示.起初在圆盘上加一恒力矩使物体以速率 u 0 = 0.6 m/s 匀速上升,如撤去所加力矩,问经历多少时间圆盘开始作反方向转动.