铅锤;
Laser-heavy plumb-bob surveying apparatus with a double controlled axial line extended technology for construction of highrise building
高层建筑激光&重锤双控轴线引伸技术
If the mass in question is a plumb bob, the horizontal component of F is important.
如果所讨论的质量是一摆锤,则重要的是F的水平分量。
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