Review centre of gravity calculation

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Homework Help Overview

The discussion revolves around calculating the center of gravity for a half octagonal prism with a small weight placed at a specific distance from the centerline. Participants are examining the centroid calculations for various shapes involved in the prism's geometry, including a trapezoid and a rectangle, and how these affect the overall center of gravity.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants are discussing the method for finding centroids of individual shapes and how to combine them to find the overall centroid of the prism. There are questions about the reference points used for measuring heights and the implications of symmetry in the shapes. Some participants are also questioning the correctness of specific equations used in the calculations.

Discussion Status

The discussion is ongoing, with participants providing feedback on each other's calculations and assumptions. There is a focus on clarifying the correct approach to measuring centroids and the impact of different reference points on the final calculation of the center of gravity. Some guidance has been offered regarding the importance of using a common reference for all shapes involved.

Contextual Notes

Participants have noted that the topmost surface of the prism is hollow, which may affect the center of gravity. There are also concerns about whether all relevant dimensions and areas have been included in the calculations, particularly regarding the bottom surface of the prism.

  • #31
Wait, I think I have it figured out now. Let me correct this and get back to you
 
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  • #32
Samiha Samin said:
Wait, I think I have it figured out now. Let me correct this and get back to you

When you do your calculations of vessel KG, remember to include not only the inclining weight, but all the gear (scales, plumb bob, mast holding the plumb bob, etc.) with which the model vessel is fitted to carry out the inclining experiment. The experiment gives the KG of the vessel as inclined, and the weight and KG of the vessel by itself must be found by removing the items used to carry out the experiment, by doing a separate calculation of their weights and KGs and subtracting from the inclined condition.
 
  • #33
SteamKing said:
When you do your calculations of vessel KG, remember to include not only the inclining weight, but all the gear (scales, plumb bob, mast holding the plumb bob, etc.) with which the model vessel is fitted to carry out the inclining experiment. The experiment gives the KG of the vessel as inclined, and the weight and KG of the vessel by itself must be found by removing the items used to carry out the experiment, by doing a separate calculation of their weights and KGs and subtracting from the inclined condition.
Okay I have found the masses of each individual parts, but when I add them up it is not equal to the mass of the whole vessel that I measured on a weighing scale. In fact it sums up to a mass that is greater than the mass of the whole vessel. Does this indicate an error in my calculation?
 
  • #34
Samiha Samin said:
Okay I have found the masses of each individual parts, but when I add them up it is not equal to the mass of the whole vessel that I measured on a weighing scale. In fact it sums up to a mass that is greater than the mass of the whole vessel. Does this indicate an error in my calculation?
Yes, I'm afraid it could.

Just out of curiosity, how much did the vessel weigh on the scale, and how much is your calculated weight?

Did you weight the vessel with or without all of the inclining experiment gear attached?
 

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