虚位移之“虚”表现何在?
刘天贵,刘全慧
What does“virtual”mean in the virtual displacement?
LIU Tian-gui,LIU Quan-hui
大学物理 . 2017, (2): 5 -7 .  DOI: 10.16854 /j.cnki.1000-0712.2017.02.002