Rigid-body rotational kinetic energy
Rotation stores kinetic energy determined by mass distribution.
Key knowledge
A rigid body’s kinetic energy decomposes into centre-of-mass translation and rotation about that centre: K=M|V_CM|²/2+ω·I_CMω/2. For fixed-axis pure rotation, K_rot=I_axisω²/2. Moments of inertia depend on the axis; parallel axes separated by distance d obey I_axis=I_CM,parallel+Md².
Values and equations
K=½M|V_CM|²+½ω·I_CMω; I_axis=I_CM,parallel+Md²
- K
- Total Newtonian kinetic energy J
- M
- Rigid-body mass kg
- V_CM
- Centre-of-mass vector velocity m s⁻¹
- ω
- Angular velocity rad s⁻¹
- I_CM,I_axis,I_CM,parallel
- Centre-of-mass inertia tensor and stated scalar moments kg m²
- d
- Perpendicular separation of parallel axes m
Conditions and scope
- Newtonian rigid body with fixed mass distribution; I_CM is expressed in the same orthonormal basis as ω.
- The scalar parallel-axis formula compares parallel axes and requires the reference axis through the centre of mass; it is not a relation for arbitrary axis orientations.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Samuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)2 sources
- University Physics Volume 1, §10.4: moment of inertia and rotational kinetic energySamuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)Textbook chapter
- University Physics Volume 1, §11.1: rolling motionSamuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)Textbook chapter
Evidence and review
Read §10.4 rotational-energy integral and axis dependence, plus §11.1 kinetic-energy decomposition for rolling. General tensor form and parallel-axis identity are disclosed mass-sum consequences using the existing inertia definition; not new experimental material constants.
2026-10-10 · /root/audit_life_earth_chemistry — independent Chemistry/Life/Earth editor. Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
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- foundation-physics-rotational-kinetic-energy
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