Moment of Inertia for a uniform wire

AI Thread Summary
The discussion focuses on calculating the moment of inertia for a composite object made of a circle and a square, both constructed from uniform wire. The moment of inertia for the square about Axis B is determined to be I=1/4 md². For the circle, the moment of inertia about its center is proposed as I=Mr², although there is uncertainty regarding its correctness. The perpendicular axis theorem is applied to find the moment of inertia for the square about a perpendicular axis, leading to a total moment of inertia calculation for the entire object. The final results indicate that the moment of inertia about Axis A is derived using the established equations and symmetry considerations.
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Homework Statement


A flat object shown here consists of a circle and square made of heavy, uniform wire and welded together at the corners of the square. The mass of the circle is M. The mass of the square is m and its side has a length d. To find the objects moment of inertia about Axis A:
a)Find Moment of inertia of the square about Axis B in its plane.
- I=1/4 md2

b)Find Moment of inertia of the circle about the axis perpendicular to its plane at its center C.
- I came up wit I=Mr2 (Not sure if its right?)

c)Use the perpendicular axis theorem to find the moment of inertia of the square about this same perpendicular axis.

d)Add to get the total moment of inertia about this Axis.

e)Use the perpendicular axis theorem again to get the moment of inertia about Axis A.

Homework Equations


I=ICM + Mh2

IZ=IX + IY (not sure how this theorem works)
 

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Actually I think I figured out B.
Iz=Ix+Iy
By symmetry Ix=Iy

So
2Ix=Iz Iz=Md^2/4
Ix=1/2Iz

Iz=md^2/8

Is this correct?
 
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