一根内壁光滑的细圆管,形状如图所示,放在竖直平面内,一个球自

一根内壁光滑的细圆管,形状如图所示,放在竖直平面内,一个球自A口的正上方高h处自由下落.第一次小球恰能抵达B点;第二次落入A口后,自B口射出,恰能再进入A口,则两次小球下的高度之比hlh2 =       

答案

4:5

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