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PhysicsRotationCalculation of M.I.Medium2 minPYQ_2020
PhysicsMediumnumerical

ABC is a plane lamina of the shape of an equilateral triangle. D, E are mid-points of AB, AC and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is I0. If part ADE is removed, the moment of inertia of the remaining part about the same axis is NI016 where N is an integer. Value of N is:

 

Question diagram: A B C is a plane lamina of the shape of an equilateral trian
Answer:
11.00
Solution:

Let mass of lamina =m, and length of side =l, then moment of inertila of lamina about an axis passing through G and perpendicular to the plane.

I0ml2

I0=kml2

Let moment of inertila of DEF=I1 about G

then, I1=I016

then,IADE=IBDF=IEFC=I2

3I2+I1=I0

3I2+I016=I0

 I2=5I016

So, Moment of inertila of DECB=2I2+I125I016+I016

=11I016

Stream:JEESubject:PhysicsTopic:RotationSubtopic:Calculation of M.I.
2mℹ️ Source: PYQ_2020

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