---
title: "Linear Mass Density — AP Physics C Mechanics Definition"
description: "Linear mass density (λ) is mass per unit length, λ = M/L or dm/dx. You need it to integrate for center of mass and rotational inertia of nonuniform rods."
canonical: "https://fiveable.me/ap-physics-c-mechanics/key-terms/linear-mass-density"
type: "key-term"
subject: "AP Physics C: Mechanics"
---

# Linear Mass Density — AP Physics C Mechanics Definition

## Definition

Linear mass density refers to how much mass is distributed along a given length. It is calculated by dividing the total mass by the length.

## Related Study Guides

- [4.1 Center of Mass ](/ap-physics-c-mechanics/unit-4/center-mass/study-guide/pleJdgx4XYiy12T34nmN)

## Review

### Related Terms

- Surface Mass Density: Similar to linear mass density, but for two-dimensional objects like sheets or films.
- Volume Mass Density (Density): The amount of mass per unit volume.
- [Tension Force](/ap-physics-c-mechanics/key-terms/tension-force): The pulling force exerted by a string, cable, or similar object when it is stretched.