Civil Engineering - Strength of Materials - Discussion


The ratio of the moment of inertia of a circular plate and that of a square plate for equal depth, is

[A]. less than one
[B]. equal to one
[C]. more than one
[D]. equal to 3π/16
[E]. none of these.

Answer: Option D


For circular plate, MI = π*d^4/64.

For square plate, MI = d^4/12.

So, Ratio = MI of circular plate/MI of square plate.

= 3*π/16.

Abhay said: (Feb 2, 2016)  
For circular plate Moment of inertia Ic = πD^4/64.

For square plate Moment of inertia is = D^4/12.

Ratio = (πD^4/64)/( D^4/12) => 3π/16.

Himzz said: (Nov 24, 2016)  
According to me, it seems option A is also right.

Roop Kumar said: (Mar 2, 2018)  
Both options D & A are correct.

Parmanand Prasad said: (May 5, 2018)  
Both A and D is correct.

Gnanasundar said: (Sep 5, 2018)  
The Answer should be 3π/16.

M.O.I of circular=πD^4/64,
M. O. I of rectangular=D^3/12,
But here depth is given equal so M. O. I of rec=D^4/12,
Circular/rectangular =3π/16.

Amarjreet Kumar said: (Aug 18, 2019)  
According to me, A is the right option.

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