Moment of inertia of 2 uniform thin rods

AI Thread Summary
To find the moment of inertia of two uniform thin rods about a specific axis, the center of mass (COM) for each rod is first identified, with the top rod's COM at y = 0.5 L and the bottom rod's COM at x = 0.5 L. The parallel axis theorem is then applied using the formula I = (1/12)ml^2 + md^2, where d represents the distance from the COM to the axis of rotation. The distance d for the bottom rod is calculated as 0.5 L - 4/9 L, while the distance for the top rod is determined as √((3/9 L)² + (0.5 L)²). This approach effectively allows for the calculation of the moment of inertia for both rods.
jisbon
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Homework Statement
Calculate the moment of inertia of 2 uniform thin rods about axis A where the figure belows shows the top view.
Relevant Equations
##I=\frac{1}{12}ml^2##
1571734403087.png


So to start off, what I will do find the center of mass of each of the rods. So for the top rod, COM is at where y= 0.5 L and COM of the rod at the bottom is at x = 0.5 L. From there, how do I proceed in finding the moment of inertia using parallel axis theorem? Do I simply treat:
##I =\frac{1}{12}ml^2+md^2##
Where d is the distance between the centre of mass and point A for each of the rods respectively? (Whereby d will be 0.5 L - 4/9 L for the bottom rod)

Thanks
 
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jisbon said:
Homework Statement: Calculate the moment of inertia of 2 uniform thin rods about axis A where the figure belows shows the top view.
Homework Equations: ##I=\frac{1}{12}ml^2##

View attachment 251651

So to start off, what I will do find the center of mass of each of the rods. So for the top rod, COM is at where y= 0.5 L and COM of the rod at the bottom is at x = 0.5 L. From there, how do I proceed in finding the moment of inertia using parallel axis theorem? Do I simply treat:
##I =\frac{1}{12}ml^2+md^2##
Where d is the distance between the centre of mass and point A for each of the rods respectively? (Whereby d will be 0.5 L - 4/9 L for the bottom rod)

Thanks
Yes. What will d be for the other rod?
 
haruspex said:
Yes. What will d be for the other rod?
Will it be ##\sqrt(({\frac{3}{9}L)}^2+(0.5L)^2)##?
 
Solved it. Thanks so much for your guidance 😄
 
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