Volumes in different dimensions

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Homework Help Overview

The discussion revolves around the concept of volumes in different dimensions, particularly focusing on the attributes of one-dimensional and higher-dimensional objects. Participants explore the implications of dimensionality on area and volume, questioning how these concepts apply to mathematical objects like lines, points, and shapes.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants express uncertainty about whether a line has area, with some suggesting it has area equal to zero. Others discuss the representation of these concepts using mathematical notation like ##dx## and ##f(x)##. There is also mention of higher-dimensional measures and the implications of completeness in measure theory.

Discussion Status

The discussion is ongoing, with various interpretations being explored regarding the attributes of different dimensional objects. Some participants provide clarifications on the definitions of points, lines, and shapes, while others raise questions about the implications of fractional dimensions and specific examples like the Koch Snowflake and Sierpenski Sponge.

Contextual Notes

Some participants note that the original inquiry was not a homework question, indicating a more exploratory nature of the discussion. There is also mention of a change in forum layout affecting the ability to mark threads as solved.

r0bHadz
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Homework Statement
Does a line from f(x) to the x-axis have any area?
Relevant Equations
not sure how to describe the area of a line
I would assume that it has some area even if it is really really small. But I guess a line implies that the left and right boundaries are going to the middle an infinite amount, so it has area =0? does anyone get what I mean?
 
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You are correct, but there is a way to represent that fact using ##dx## or ##\delta x## and ##f(x)##. They might want that for an answer.
 
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FactChecker said:
You are correct, but there is a way to represent that fact using ##dx## or ##\partial x## and ##f(x)##. They might want that for an answer.
oh wasn't a homework question, was just wondering myself. I appreciate it though! Also, I use to be able to mark my thread as solved with the old layout. Where is the button on this new one??
 
r0bHadz said:
oh wasn't a homework question, was just wondering myself. I appreciate it though! Also, I use to be able to mark my thread as solved with the old layout. Where is the button on this new one??
Looks as though there is NO such button now.
 
r0bHadz said:
I would assume that it has some area even if it is really really small. But I guess a line implies that the left and right boundaries are going to the middle an infinite amount, so it has area =0? does anyone get what I mean?
No, the volume is zero. It has a length, but no area.
 
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To generalize, an n-dimensional object ( I think we need to assume completeness of measure) has , for k integer, k>0, (n+k)- dimensional measure equal to 0. The completeness is used to make sure it is measurable.
 
fresh_42 said:
No, the volume is zero. It has a length, but no area.
And to elaborate, a point is a mathematical object of dimension zero -- no length, width, or height.
A line is one-dimensional, and has length only.
A rectangle (or triangle, circular disk, or other similar plane object) is two-dimensional, and has area as an attribute.
A cube (or sphere or other solid object) is three-dimensional, and has volume as an attribute.

Things get more complicated if you allow fractional dimensions, with so-called space filling curves such as the Koch Snowflake or the Sierpenski Sponge. The Koch Snowflake can be shown to be a bounded curve (i.e., entirely contained within some rectangle in the plane) that has an infinite length. The Sierpenski Sponge can be also shown to have an infinite surface area, while being enclosed in some box in three-dimensional space.
 
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