Radius x Height: Unpacking the Mystery of Volume in Cubes

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Discussion Overview

The discussion revolves around the dimensional analysis of volume, specifically in the context of the formula for the volume of a cone. Participants explore how multiplying different dimensions, such as radius and height, results in cubic units, questioning the mathematical principles behind this concept.

Discussion Character

  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • One participant questions how the volume of a cone, expressed as 1/3 pi R^2 h, results in cubic units, noting that height contributes a third dimension but expressing confusion about the multiplication of dimensions.
  • Another participant asserts that multiplying a height by a squared radius is valid and explains that different length measurements can be combined to yield volume, emphasizing that all dimensions represent length.
  • A third participant mentions that dimensional analysis can serve as a method for error checking, indicating that arriving at square units instead of cubic units suggests a mistake in calculations.
  • A repeated post reiterates the initial question about dimensionality and emphasizes the importance of distinguishing between numbers and their units in dimensional analysis.
  • One participant clarifies that multiplying three length measurements together will always yield volume units, regardless of whether the lengths are the same.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the multiplication of dimensions and the resulting units, indicating that the discussion contains multiple viewpoints and remains unresolved on certain aspects of dimensional analysis.

Contextual Notes

Some participants may not fully distinguish between numerical values and their associated units, which could lead to confusion in understanding dimensional analysis.

squarkman
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Hi,
The volume of a cone is 1/3 pi R^2 h.
Why then is the answer in units cubed. Certainly the h is contributing a third dimension but in general math you don't see this happening
X^2 * Z = X^3
but the below is true
X^2 * X = X^3

Can a radius be multiplied by a height to make the dimension increase?
What's going on here?
Thx
 
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Of course you can multiply by a height to make the dimension increase. X^2 * X = X^3 means you are multiplying the same variable. You can replace with Z and your new value is not X^3, but ZX^2 which has units of length cubed. Think of a rectangle with width X, length Y, and height Z. Surely you multiply them all together and you get length-cubed dimensions. X, Y, and Z all represent different lengths, but they represent length none-the-less.
 
In fact, this can be used for error checking. If you arrived at an answer that should be volume and you end up with units of length squared, you know you did something wrong.
 
squarkman said:
Hi,
The volume of a cone is 1/3 pi R^2 h.
Why then is the answer in units cubed. Certainly the h is contributing a third dimension but in general math you don't see this happening
X^2 * Z = X^3
but the below is true
X^2 * X = X^3

Can a radius be multiplied by a height to make the dimension increase?
What's going on here?
Thx
You are not distinguishing between numbers and their units. (X m)2(Z m)= (X2Z) m3, just as (X m)(Y m)(Z m)= (XYZ) m3.

If you multiply three length measurements together, the result is alway in volume units whether the lengths themselves are the same or not.
 

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