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Q & A: Radius of gyration and second moments of area

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Most recent answer: 10/22/2007
Q:
What are the pratical applications of the radius of gyration and the second moments of area and volume. We are studing this subject in calculus (although, it does relate to pysics) and i was just wonering if it had any real world applications. Thanks.
- Nicole (age 18)
CA
A:
Hi Nicole,

Both the radius of gyration and the second moment of area are used to help us describe how objects rotate. The moment of inertia of an object about an axis relates the angular velocity of an object (how fast itís spinning) to how much angular momentum it has. That tells us how much torque must be exerted on the object to get it spinning at some rate, or how much energy it has when itís spinning at some rate. The moment of inertia is computed by weighting the second moment of the area with the density of the material the object is made from. We already have two very nice answers on this web site about  and .

Tom

(published on 10/22/2007)

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