Mass, Moments and Center of Mass

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Homework Help Overview

The problem involves calculating the mass of a square plate with a specified areal density that varies with distance from the diagonals. The original poster expresses confusion regarding their diagram and its relation to the problem's requirements.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the correct interpretation of the distance r in relation to the diagonals of the square. There is an exploration of how to properly represent this in a diagram, with suggestions to consider the perpendicular relationship of r to one diagonal.

Discussion Status

The discussion is ongoing, with participants providing clarifications about the geometry involved. Some guidance has been offered regarding the interpretation of the problem, but no consensus has been reached on the diagram's accuracy or the approach to take.

Contextual Notes

There is an indication that the original poster's diagram may not align with the problem's requirements, and participants are attempting to clarify the definitions and relationships involved without providing a definitive solution.

dimpledur
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Homework Statement


A square plate with edge a cm and areal density kr g/cm^2, where r is the distance (in centimetres) from P to one of the diagnals of the square.

Find the mass.

The Attempt at a Solution


I know my diagram is wrong, and I know what the correct one looks like. However, I do not see how my diagram does not work... All of the diagnals meet at the centre which in my diagram is the origin. Hence, and radius extends from all the diagnals to position P.

Any ideas?

math-1.jpg
 
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hi dimpledur! :smile:

the diagonal is one of the two lines from one corner to the opposite corner :wink:
 
Yeah, so in my diagram r extends from both diagnals, does it not? I'll provide another picture.
 
yes, so choose one of the diagonals, as in the question :wink: …
dimpledur said:
… where r is the distance (in centimetres) from P to one of the diagnals of the square.
 
math2.jpg


Here, r extends from the very center where the diagnals meet, and hence touches both.. hmm
 
tiny-tim said:
yes, so choose one of the diagonals, as in the question :wink: …

So the easiest way to appreach this would be to rotate the square such that r is perpendicular to the diagnal of the square?
 
dimpledur said:
Here, r extends from the very center …

erm, noooo :redface: …

r is perpendicular to one diagonal
 
Okay, thanks.
 

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