A generalization of the second Pappus–Guldin theorem

This paper deals with the question of how to calculate the volume of a body in R3 when it is cut into slices perpendicular to a given curve. The answer is provided by a formula that can be considered as a generalized version of the second Pappus–Guldin theorem. It turns out that the computation beco...

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Main Author: Harald Schmid
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Results in Applied Mathematics
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2590037425000019
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author Harald Schmid
author_facet Harald Schmid
author_sort Harald Schmid
collection DOAJ
description This paper deals with the question of how to calculate the volume of a body in R3 when it is cut into slices perpendicular to a given curve. The answer is provided by a formula that can be considered as a generalized version of the second Pappus–Guldin theorem. It turns out that the computation becomes very simple if the curve passes directly through the centroids of the perpendicular cross-sections. In this context, the question arises whether a curve with this centroid property exists. We investigate this problem for a convex body K by using the volume distance and certain features of the so-called floating bodies of K. As an example, we further determine the non-trivial centroid curves of a triaxial ellipsoid, and finally we apply our results to derive a rather simple formula for determining the centroid of a bent rod.
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spelling doaj-art-b6db7fad8f7b4ed78cca3d403008fb502025-08-20T02:47:33ZengElsevierResults in Applied Mathematics2590-03742025-02-012510053710.1016/j.rinam.2025.100537A generalization of the second Pappus–Guldin theoremHarald Schmid0University of Applied Sciences Amberg-Weiden, Amberg, GermanyThis paper deals with the question of how to calculate the volume of a body in R3 when it is cut into slices perpendicular to a given curve. The answer is provided by a formula that can be considered as a generalized version of the second Pappus–Guldin theorem. It turns out that the computation becomes very simple if the curve passes directly through the centroids of the perpendicular cross-sections. In this context, the question arises whether a curve with this centroid property exists. We investigate this problem for a convex body K by using the volume distance and certain features of the so-called floating bodies of K. As an example, we further determine the non-trivial centroid curves of a triaxial ellipsoid, and finally we apply our results to derive a rather simple formula for determining the centroid of a bent rod.http://www.sciencedirect.com/science/article/pii/S2590037425000019Pappus–Guldin theoremCentroid curveFloating bodyVolume distanceElastic rod
spellingShingle Harald Schmid
A generalization of the second Pappus–Guldin theorem
Results in Applied Mathematics
Pappus–Guldin theorem
Centroid curve
Floating body
Volume distance
Elastic rod
title A generalization of the second Pappus–Guldin theorem
title_full A generalization of the second Pappus–Guldin theorem
title_fullStr A generalization of the second Pappus–Guldin theorem
title_full_unstemmed A generalization of the second Pappus–Guldin theorem
title_short A generalization of the second Pappus–Guldin theorem
title_sort generalization of the second pappus guldin theorem
topic Pappus–Guldin theorem
Centroid curve
Floating body
Volume distance
Elastic rod
url http://www.sciencedirect.com/science/article/pii/S2590037425000019
work_keys_str_mv AT haraldschmid ageneralizationofthesecondpappusguldintheorem
AT haraldschmid generalizationofthesecondpappusguldintheorem