Moment of inertia

Moment of inertia quantifies the rotational inertia of an object, i.e. its inertia with respect to rotational motion, in a manner somewhat analogous to how mass quantifies the inertia of an object with respect to translational motion.

Related Topics:
Rotational inertia - Mass - Inertia

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In general, an object's moment of inertia depends on its shape and the distribution of mass within that shape: the greater the concentration of material away from the object's centroid, the larger the moment of inertia. It also varies depending upon the axis of rotation specified; values relative to the object's centroid are typically taken as baseline values. See the list of moments of inertia for specific examples. The parallel axes theorem can be used to determine moments of inertia relative to displaced axes of rotation.

Related Topics:
Centroid - Axis - Rotation - List of moments of inertia - Parallel axes theorem

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Rotational versions of Newton's second law and the formulas for momentum and kinetic energy, use moment of inertia in place of the mass of an object (with torque, angular velocity and angular acceleration replacing force, velocity and acceleration, respectively).

Related Topics:
Newton's second law - Momentum - Kinetic energy - Torque - Angular velocity - Angular acceleration - Force - Velocity - Acceleration

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Moment of inertia is often represented by the letter I (capital i).

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It should not be confused with the second moment of area or area moment of inertia, which is a property of a shape that is used to predict its resistance to bending and deflection. Most structural engineers, however, will refer to the second moment of area or area moment of inertia as simply the moment of inertia.

Related Topics:
Second moment of area - Bending - Deflection

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