Calculating Volume of a Cylindrical Wedge

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Homework Help Overview

The problem involves calculating the volume of a cylindrical wedge, with specific boundaries defined by the equation x + z = a. Participants are discussing the implications of this boundary on the volume calculation and the limits of integration.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring the interpretation of the boundary condition x + z = a and questioning whether the volume should be halved based on this definition. There is also discussion about the limits of integration for x, y, and z, and whether y should be restricted to positive values.

Discussion Status

The discussion is ongoing, with participants providing insights into the implications of the boundary conditions and limits. Some have suggested that the interpretation of the plane may affect the volume calculation, while others are clarifying their understanding of the geometric representation of the wedge.

Contextual Notes

There is a mention of a reference that presents the wedge as having a full volume, which contrasts with the interpretations being discussed. Participants are also considering the implications of the variable a being positive or negative on the boundaries of the wedge.

unscientific
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Homework Statement



The problem is attached in the picture.



The Attempt at a Solution



What bothers me is that they say the wedge is bounded by x + z = a. Doesn't this imply that the calculated volume should only be half of what is written in the answers? I'm aware that the plane x + z = a can refer to either the left (negative) side or the right (positive) side. Do we choose one or simply take both?

Limits for x: 0 to a
Limits for y: 0 to √4ax
Limits for z: 0 to a-x


However, in http://mathworld.wolfram.com/CylindricalWedge.html the wedge is given as the full volume.
 

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You have two possibilities: if a>0, then x>0 and z>0. If a<0, then also x<0 and z<0. No value of a works for both regions.
 
unscientific said:

Homework Statement



The problem is attached in the picture.



The Attempt at a Solution



What bothers me is that they say the wedge is bounded by x + z = a. Doesn't this imply that the calculated volume should only be half of what is written in the answers? I'm aware that the plane x + z = a can refer to either the left (negative) side or the right (positive) side. Do we choose one or simply take both?

Limits for x: 0 to a
Limits for y: 0 to √4ax
Limits for z: 0 to a-x

Assuming ##a>0##, the slanted plane is the "roof" of the solid. I see no reason to limit ##y## to only being positive.
 
LCKurtz said:
Assuming ##a>0##, the slanted plane is the "roof" of the solid. I see no reason to limit ##y## to only being positive.

I see! I initially thought that the x + z = a plane refers to the vertical plane i.e. the x-z plane. But now that you mention it, it actually refers to the plane that is sloping downwards from z = a to x = a, like a ramp.
 

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