- #1

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Hi..

I've got a problem about moment inertia. I don't understand about looking the distance of centroid (y). I am still confucing about the formula of "y" in Moment Inertia. Can you shows me about the formula of y or if any thread for this before, I am glad to see it too.Thanx's for your help..

Known : You can see the dimension and the picture in my attachment

Asking: How is to calculate y ?? Is the formula same to all geometry??

I = y dA

Cross section

Total Area: - A =>40*60=2400

- Ay =>72000

Inside Area:-A=> -20*30=-600

- Ay => -21000

I've got a problem about moment inertia. I don't understand about looking the distance of centroid (y). I am still confucing about the formula of "y" in Moment Inertia. Can you shows me about the formula of y or if any thread for this before, I am glad to see it too.Thanx's for your help..

**I still don't know how to find put y =30 and 35**

## Homework Statement

Known : You can see the dimension and the picture in my attachment

Asking: How is to calculate y ?? Is the formula same to all geometry??

## Homework Equations

I = y dA

## The Attempt at a Solution

Cross section

Total Area: - A =>40*60=2400

**- y => 30****Why is it 30?**- Ay =>72000

Inside Area:-A=> -20*30=-600

**-y =>35****Why is it 35?**- Ay => -21000