A rotating rigid body has kinetic energy associated with its rotation.
Difficulty
Beginner
Read time
5 min
Prerequisites
Basic algebra and consistent SI units
Source
OpenStax, College Physics 2e, §10.4 (Paul Peter Urone and Roger Hinrichs)Textbook reference retained from the OpenFormulaGraph dataset; adaptation credits and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted the notation, explanations, assumptions, and topic placement, and expanded the numerical check into a worked example. The textbook section link was corrected.
A rotating rigid body has kinetic energy associated with its rotation. Increasing angular speed increases this energy quadratically. The moment of inertia must be taken about the same axis as the angular speed.
| Symbol | Meaning | Units |
|---|---|---|
| Rotational kinetic energy | ||
| Moment of inertia about the rotation axis | ||
| Angular speed |
Estimate stored rotational energy.
Compare energy requirements at different speeds.
A rotor has moment of inertia 4.00 kg·m² about its fixed shaft and spins at 3.00 rad/s. Find its rotational kinetic energy.
Textbook reference retained from the OpenFormulaGraph dataset; adaptation credits and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted the notation, explanations, assumptions, and topic placement, and expanded the numerical check into a worked example. The textbook section link was corrected.
Assumptions
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