- #1
How is the mass of the composite shape calculated using centroids and statics?
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Discussion Overview
The discussion revolves around the calculation of mass for a composite shape using centroids and statics, focusing on the dimensions of rectangles and triangles involved in the shape. Participants are examining the correctness of specific dimensions and mass calculations based on given area densities.
Discussion Character
- Technical explanation, Debate/contested, Mathematical reasoning
Main Points Raised
- One participant questions the dimensions used for the rectangle, specifically the 210 dimension, suggesting it should be based on the diameter rather than the radius, proposing a corrected dimension of 300.
- Another participant agrees with the correction regarding the rectangles and suggests that the correct value for y bar should be 95.6.
- A participant expresses confusion about how mass and y bar were derived given only the area densities of the components.
- One participant explains that the mass can be calculated by multiplying the area (derived from dimensions) by the area density, noting that the components are treated as surfaces of zero thickness despite an illustration suggesting otherwise.
- A participant indicates a lack of expertise in the topic, hoping for further assistance from others.
Areas of Agreement / Disagreement
There is disagreement regarding the dimensions used in the calculations, with multiple participants proposing different values. The discussion remains unresolved as participants express differing views on the correct approach and calculations.
Contextual Notes
Participants have not reached a consensus on the correct dimensions or the method for calculating mass and y bar, indicating potential limitations in the information provided and assumptions made about the shape's geometry.
Who May Find This Useful
Individuals interested in engineering, particularly those dealing with statics and composite shapes, may find this discussion relevant.
- #2
Tom.G
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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 45o angle, each triangle is one half of a square of 75 on a side, and there are two triangles.
Due to the 45o angle, each triangle is one half of a square of 75 on a side, and there are two triangles.
- #3
physocs1
- 16
- 0
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
And the answer is wrong as well it should be 95.6 for y bar
Thank-you
- #4
physocs1
- 16
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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
- #5
Tom.G
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You just exceeded my knowledge (I'm an electronics guy). Let's hope someone else jumps in here to help.
- #6
physocs1
- 16
- 0
Okay thanks for the first post
- #7
JBA
Science Advisor
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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.
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