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Physics

Rod Moment of Inertia Calculator

Find inertia of a thin uniform rod about its midpoint.

SI units shown beside each fieldIdeal model explained below
Physics lab
Physics lab

Use the units beside each input and review the model assumptions.

See the method

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Your calculated quantity

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter mass, rod length.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

Input reference and sample values

Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.

InputFormat and unitsSample
MassNumeric value. Unit: kg. Must be greater than zero.10
Rod lengthNumeric value. Unit: m. Must be greater than zero.2

Result for these sample inputs

3.33333333 kg·m²

Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.

The method, explained

Moment of inertia = mass × length²/12.

A WORKED EXAMPLE

Using mass = 10 kg, rod length = 2 m, the result is 3.33333333 kg·m². Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Axis is perpendicular to the rod through its center. An idealized educational model using the stated SI units. Real systems may need additional forces, losses or experimental measurements. Not a safety or equipment specification.

Methodology maintained by ClarityKit. How these tools are built and checked.