如图1所示,一小球用轻绳悬于O点,用力F拉住小球,使悬线保持偏离

如图1所示,一小球用轻绳悬于O点,用力F拉住小球,使悬线保持偏离竖直方向750角,且小球始终处于平衡状态。为了使F有最小值,F与竖直方向的夹角θ应该是(      ) 

A.00            B.150       

C.450           D.900  

 

答案

B

解析:略

 

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