Very basic statics question/moment of inertia

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When calculating the moment of inertia about the y-axis for a triangular shape in the second quadrant, the formula hb^3/12 can still be used, but the definitions of 'b' and 'h' must be clear. The formula is specifically applicable to right triangles, and it is essential to ensure that one side is collinear with the y-axis. The position of the triangle relative to the x-axis or its quadrant does not affect the validity of the formula. Additional resources are available for calculating the moment of inertia for more general triangular shapes. Understanding these nuances is crucial for accurate calculations in statics.
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Statics: If computing the moment of inertia about the y-axis of a triangular shape in the 2nd quadrant(not touching the x-axis); would i still use hb^3 /12
 
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encorelui2 said:
Statics: If computing the moment of inertia about the y-axis of a triangular shape in the 2nd quadrant(not touching the x-axis); would i still use hb^3 /12

Yes, you would, but be careful which sides you use for 'b' and 'h'. You haven't specified which is measured along the x-axis and which is measured along the y-axis. This formula only works for right triangles, incidentally.

http://en.wikipedia.org/wiki/List_of_area_moments_of_inertia
 
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encorelui2: So far, your formula looks correct. And, it is not limited to right triangles.

It does not matter whether it touches the x-axis or not. And it does not matter what quadrant it is in. It only needs to have one side coincident (collinear) with the y axis, assuming b is the horizontal width of your triangle.
 
nvn said:
encorelui2: So far, your formula looks correct. And, it is not limited to right triangles.

It does not matter whether it touches the x-axis or not. And it does not matter what quadrant it is in. It only needs to have one side coincident (collinear) with the y axis, assuming b is the horizontal width of your triangle.

I apologize for not posting more complete information, but the OP's formula for the moment of inertia of a triangle is indeed only applicable to right triangles. The following link gives formulas for the area properties for more general triangular shapes:

http://www.efunda.com/math/areas/triangle.cfm
 

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