Moment of Inertia - Find Area Around Y-Axis

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The discussion focuses on calculating the moment of inertia of a specified area about the y-axis, defined by the curve y²=2x within the bounds of 0m
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This is my first time posting in this site so if I left out any information or the information needs to be formatted differently I apologize ahead of time.

Homework Statement



Determine the moment of inertia of the area about the y axis.

The curve is represented by y2=2x, and the shaded region is the smaller area above the curve.

0m<x<2m
0m<y<2m

Homework Equations



Is the parallel axis theorem needed? If it is, why is the reason?

The Attempt at a Solution



Since the problem asks for moment of Intertia about the y-axis

1. Iy= ∫x2dA.

2. I chose my dA to be xdy because I need to find a "bar" perpendicular to the axis I am trying to find the moment of inertia about.

3. Solved

Iy= ∫x2ydx.
I substituded (2-/sqrt(2x)) for y and solved for the integral from (0<x<2)

My answer I got was 2.13m4 and the answer is incorrect.

Is my process correct or do I need to find different limits of integration?
 
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I don't know how to close a thread, I found out my error was in the integration process.

Solved, Iy= .762m^4.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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