线密度

线密度，或者更准确地说，线性质量密度，是指物质的质量与长度的比值。线密度这个术语通常用来描述一维物体的特性，但是线密度也可以用来描述三维物体沿着某一特定维度的密度。

The Linear Density, or more precisely, the linear mass density, of a substance is its mass per unit length. The term linear density is most often used when describing the characteristics of one-dimensional objects, although linear density can also be used to describe the density of a three-dimensional quantity along one particular dimension.