From a20581b57eb5a5b6c6f2809a216d5b7dcf133af0 Mon Sep 17 00:00:00 2001 From: Tyler Clarke Date: Wed, 16 Apr 2025 09:03:02 -0400 Subject: [PATCH] start on 16.7: will finish later --- site/default.html | 12 +++++++----- site/posts/multivariable-thomas-16.7.html | 23 +++++++++++++++++++++++ 2 files changed, 30 insertions(+), 5 deletions(-) create mode 100644 site/posts/multivariable-thomas-16.7.html diff --git a/site/default.html b/site/default.html index be8fe46..a122e73 100644 --- a/site/default.html +++ b/site/default.html @@ -36,11 +36,13 @@
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+ Hello again! We're on the penultimate section in the chapter and in the entire book. In this section, we're covering Stokes' Theorem. Stokes' theorem + is an application of Green's theorem in 3 dimensions. This is much harder to visualize, but essentially, with Stokes' theorem, we can find the circulation of + a vector field on a curved surface. The critical idea is that, for a smooth open surface `S` with a smooth boundary curve `C`, the circulation about + `C` is the surface integral of the curl over `S`: `int_C F cdot dr = INT INT_k (grad times F) cdot k dA`. This has an interesting consequence: + the circulation about any two open surfaces with the same boundary curve is the same. +

+

+ Let's do an example. Take the hemisphere with radius 2 above the plane `x - z = 0`, centered on origin: what is the circulation of the vector field + `F(x, y, z) = \[-y, x, z]` about this surface? In 2 dimensions this is a somewhat complicated integral to perform, but Stokes' theorem allows us to reduce + it to a single dimension, if we can parameterize the boundary curve. The plane parameterization in 2 variables is obviously `p(u, v) = \[u, v, u]`, + and the sphere is `s(u, v) = \[2cos(u)sin(v), 2sin(u)sin(v), 2cos(v)]`. This gives us three equations for the intersection: `u = 2cos(u)sin(v)`, `v = 2sin(u)sin(v)`, + and `u = 2cos(v)`. +

+[/] +[=author "Tyler Clarke"] +[=date "2025-4-12"] +[=subject "Calculus"] +[=title "Multivariable Exam 3 Review: Thomas 16.7"] +[=unpub] +[#post.html] \ No newline at end of file