Moment of inertia of triangle rotated about y axis

In summary, the conversation involves a person seeking help with setting up a triple integral to find the moment of inertia of a point mass at a given distance from a rotation axis. They mention having 6 exams and not having enough time to figure it out on their own. Another person responds, saying they cannot help due to forum policy.
  • #1
Carnivroar
128
1
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Similar to my other thread https://www.physicsforums.com/showthread.php?t=557750

I think in this case I need to use triple integrals

But what is the integrand and limits?

Can someone please help me set it up?

Here's all I know

Code:
∫∫∫dydx

Please help I have my final next wednesday.
 
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  • #2
Find the moment of inertia. What is the moment of inertia of a point mass dm at distance r from the rotation axis? The triangle consist of small masses, and you need to integrate their contribution.
ehild
 
  • #3
I don't know :(
 
  • #4
I have 6 exams this week and my physics exam is tomorrow so please just walk me through this problem. I have no time left to spend trying to figure it out.
 
Last edited by a moderator:
  • #5
Carnivroar said:
I have 6 exams this week and my physics exam is tomorrow so please just walk me through this problem. I have no time left to spend trying to figure it out.

I can not do, sorry. The policy of the Forums does not allow it.

ehild
 

Related to Moment of inertia of triangle rotated about y axis

1. What is the moment of inertia of a triangle rotated about the y-axis?

The moment of inertia of a triangle rotated about the y-axis is a measure of its resistance to rotational motion around this axis. It is denoted by the symbol Iy and is calculated by multiplying the mass of the triangle by the square of its distance from the y-axis.

2. How is the moment of inertia of a triangle rotated about the y-axis different from that of a rectangle?

The moment of inertia of a triangle rotated about the y-axis is different from that of a rectangle because of their different shapes. While a rectangle has a constant moment of inertia regardless of its orientation, the moment of inertia of a triangle varies depending on its rotation due to its uneven distribution of mass.

3. What is the formula for calculating the moment of inertia of a triangle rotated about the y-axis?

The moment of inertia of a triangle rotated about the y-axis can be calculated using the formula Iy = (1/36) x m x h2 x (a2 + 4b2), where m is the mass of the triangle, h is the distance from the y-axis to the base of the triangle, and a and b are the dimensions of the triangle's base and height, respectively.

4. How does the position of the triangle's centroid affect its moment of inertia when rotated about the y-axis?

The position of the triangle's centroid, which is the point where all its mass is concentrated, affects its moment of inertia when rotated about the y-axis. The further the centroid is from the axis of rotation, the higher the moment of inertia will be, and vice versa.

5. Can the moment of inertia of a triangle rotated about the y-axis be negative?

No, the moment of inertia of a triangle rotated about the y-axis cannot be negative. It is always a positive value since it represents the resistance to rotation, and rotation is always a positive/angular motion.

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