How is the mass of the composite shape calculated using centroids and statics?

[physocs1]

Hi can anyone explain how in this solution they were getting for the rectangle 175x210.
And how they split the triangles

Thank you

 

[Tom.G]

The 210 dimension was INCORRECTLY arrived at by using the Radius of the cutout. They should have used the Diameter and the the 210 should be 300.

Due to the 45^o angle, each triangle is one half of a square of 75 on a side, and there are two triangles.

 

[physocs1]

Yea that's what I thought as well for the rectangles. 175x300
And the answer is wrong as well it should be 95.6 for y bar

Thank-you

 

[physocs1]

I'm not understanding how they were able to obtain the mass and y bar since they only gave out this
For 1=24kg/m^2
2=36kg/m^2

 

[Tom.G]

You just exceeded my knowledge (I'm an electronics guy). Let's hope someone else jumps in here to help.

 

[physocs1]

Okay thanks for the first post

 

[JBA]

The area of each can be calculated from the dimensions, so their mass is simply obtained by multiplying (kg = kg/mm^2 x mm^2). They are treating both components as surfaces of zero thickness, even though the illustration shows the end plate as though it has a thickness.