Volume of Paraboloid-Bounded Solid in Cylindrical Coordinates?

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Homework Help Overview

The discussion revolves around finding the volume of a solid bounded by a paraboloid and a cylinder, specifically under the paraboloid z = x^2 + y^2, above the xy-plane, and inside the cylinder defined by x^2 + y^2 = 2y. The problem is approached using cylindrical coordinates.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to determine the limits of integration in cylindrical coordinates, expressing uncertainty about eliminating y and finding the range for r. Some participants suggest that the outer limit corresponds to the cylinder and the inner limit to the paraboloid, while also noting the need to consider the jacobian in the integral.

Discussion Status

The discussion is active, with participants exploring different aspects of the problem. Guidance has been offered regarding the limits of integration and the importance of the jacobian, but there is no explicit consensus on the final approach yet.

Contextual Notes

Participants are navigating the transition to cylindrical coordinates and addressing the constraints posed by the problem's geometry, including the relationship between the paraboloid and the cylinder.

naspek
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Find the volume of the solid that lies under the paraboloid z = x^2 + y^2, above xy plane,
and inside the cylinder x^2 + y^2 = 2y

First, i try to find the range..
i transfer it to cylindrical coordinates..

sqrt(y^2)=<z<=r^2
i don't know how to find r
i know that phi is from 0 to 2pi because it's paraboloid right?
how am i going to eliminate y? because, y cannot exist in the cylindrical coordinate..
 
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the outer r limit will be the cylinder, the inner r limit the parabliod, express the inner limit as r(z)

the xy plane means the lower limit for z will be z=0

phi will be from 0 to 2pi, as there is nothing in the problem to limit the angular range, so you must integrate over the whole range
 
don't forget the jacobian in the integral either
 
got it! thank u very much! =)
 

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