# Polar moment of Inertia (J)



## jillhill (Apr 6, 2011)

Does anyone know when to use the Polar moment of Inertia (J) J=Ix+Iy???


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## sac_engineer (Apr 7, 2011)

jillhill said:


> Does anyone know when to use the Polar moment of Inertia (J) J=Ix+Iy???


Polar moment of inertia barely applies to statics or civil engineering. It's more common in dynamics. Don't worry about it for the PE exam.


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## civilized_naah (Apr 11, 2011)

jillhill said:


> Does anyone know when to use the Polar moment of Inertia (J) J=Ix+Iy???


Torsion problems utilize polar moment of inertia for stress and deformation calculations.


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