Linear density, linear mass density or linear mass is a measure of mass per unit of length, and it is a characteristic of strings or other one-dimensional objects. The SI unit of linear density is the kilogram per metre (kg/m). It is defined as:
where μ is the linear density of the object, m is the mass, and x is a coordinate along the (one dimensional) object.
For the common case of a homogeneous substance of length L and total mass m, this simplifies to:
The term linear density also refers to how dense a line is drawn.
