关键词: 抛绳器, 稳定状态, 受力分析, 动静法

Abstract: A popular toy string launcher can make the string floating in the air by forcing it to move tangentially. The dynamic-static method is employed to explain the mechanism as well as deduce the shape equation of the string in steady state suspension. The conditions for the launcher to work properly are also given. It is revealed that when the string configuration has a horizontal symmetric axis, the span length gets its maximum. The maximum span length is positively correlated with the ratio of resistance to gravity. 

Key words:  string launcher, steady state, force analysis, dynamic-static method