Questions tagged [stokes-theorem]
Stokes' theorem is a result about integration of differential forms.
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Prove Green Theorem using Gauss Theorem
Problem. Consider the General Stokes Theorem and $M$ a submanifold of $\mathbb{R}^{n}$, with boundary orientable.
(a) Prove the Green Theorem
$$\int_{M}(g_{x} - f_{y})dxdy = \int_{\partial M} ...
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20 views
Calculate line integral in a vector field
I have the following problem and I'm not able to solve it.
Given $F(x,y,z) = (1-2z, 0, 2y)$, calculate the line integral of C, where C is the contour of the surface. $S=\{(x,y,z) / x\geq 0, y \geq 0, ...
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Stokes' theorem proof (is it acceptable?)
Is this an acceptable proof for Stokes' theorem? I'm currently creating my own Multivariable Calculus course and this is what I have for the proof.
Also, I copied this from my TeX file so apologies ...
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What does the right hand side of this Stokes' theorem mean?
I'm reading Warner. "Foundations of Differentiable Manifolds and Lie Groups." I don't understand what the right hand side of the formula in the following theorem means.
4.9 Stokes' Theorem II $\;$ ...
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Reference request on an equation while studying Stokes steam-functions
I came across this equation while studying Stokes steam-functions and I'm not sure how its derived.
The equation is
$$(r^2-\frac{a^3}{r})\sin^2(\theta)=b^2$$
I believe it is the equation of a ...
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21 views
how to calculate $\int_C~ydx + zdy + xdz$, where $C$ is oriented counterclockwise, as viewed from above. ??
Let $C$ be the boundary of the portion of ${z = x
^2 + y
^2}$ below the plane
{$6x + 2y + z = 20$}. Find
$\int_C~ydx + zdy + xdz$, where $C$ is oriented
counterclockwise, as viewed from ...
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Show $\int_{dM} w=\int_M dw$, use $d(w|_M)$ not $w\in \Bbb A(\Bbb R^3)$ , $w|_M \in \Bbb A(M)$.
Let $w \in \Bbb A^1(\Bbb R^3)$, $w=xzdy-yzdx$, $M=\{z=f(x^2+y^2\} over $x^2+y^2 \leq \Bbb R^2$.
Illustrate Stoke's theorem with $(M,w|M)$.
For easier use $f(x)=x$.
Show $\int_{dM} w=\int_M dw$, use $...
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1answer
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Proving Fundamental Theorem of Calculus given Stokes' Theorem
Accepting Stokes' theorem (101) as a premise, how do I prove the fundamental theorem of calculus (102)? I know that the FTC is a straightforward specialization of Stokes' theorem and so proving $\text{...
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1answer
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Prove Poincaré Lemma for $1$-form
Let $U\subseteq\mathbb{R}^n$ be an open set that contains $0$, and for all $t\in[0,1]$ and $ x\in U$, $tx\in\mathbb{R}^n$. Show that every closed differentiable 1-form $w$, (i.e. $dw=0$) is an exact ...
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Can the Gauss-Bonnet theorem be proven from Stokes's theorem?
In a comment to this question, John Ma claims that the Gauss-Bonnet theorem can be proven from Stokes's theorem, but does not explain how.
For two dimensions, Stokes's theorem says that for any ...
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1answer
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Question on the proof of Stokes' Theorem in Spivak
The following is a quick outline of the proof of Stokes' Theorem as found in a Comprehensive Introduction to Differential Geometry Vol. 1 by Spivak.
Theorem (Local Stokes' Theorem). Let $M$ be a ...
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1answer
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Interpretation of stokes theorem
I recently solved the following task:
Let $A = [0,1]^3$ and $\omega = \dfrac{x_1^2 x_2^3}{1+x_3^2} \ dx_1 \wedge dx_3$ Show that this fulfills stokes theorem by showing that $\displaystyle \int_A \ d\...
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1answer
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Calculating a flux integral using Stokes vs. directly
Let $G=\{(x,y,z)\in\mathbb R^3|x^2+y^2=1 , \quad 0\leq z\leq 1\}$
Let $f: \mathbb R^3\to\mathbb R^3,\quad f(x,y,z)=\begin{pmatrix}yz^2\\-x\\ye^z\end{pmatrix}$
Calculate $\int_M curl(f)\cdot n dS$ ...
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Evaluate $\oint_C F.dr$ where $F = (x-z)i +(2y)j +(x+z)k$
I'm having trouble figuring out
$$
\oint_C \underline{F} \cdot d\underline{r},
$$
where $\underline{F} = (x-z)\underline i +2y\underline j +(x+z)\underline k$ and in which $C$ is a closed path in the $...
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1answer
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Why is it that the surface integral of the flux of a vector field is the same as the surface integral of the vector field itself?
In other words, this:
http://www.math.ucla.edu/~archristian/teaching/32b-w17/week-7.pdf
Is this just a definition because what we really care about is how much the vectors are "pushing" through the ...
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1answer
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integral of a k-form over an oriented compact manifold
I see in my course the following theorem:
If $\omega$ is an exact k-form over an oriented compact manifold M of dimension $k$, then $\int_M \omega=0$.
I don't have a proof of this theorem and I ...
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0answers
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Flux of curl of a vector field through cross section of a sphere
Suppose $R>0$, $M$ be the sphere centered at the origin with radius $R$, $M=S^2(0,R)$, and $\Gamma=\{(x,y,z)\in M:x+y+z=1\}$. I have to prove that, with the appropriate orientation of $Gamma$:
$$\...
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An intuitive explanation for Green theorem and Divergence theorem
As my vector calculus exam is getting closer, I'm looking for intuitive ways to think about the different theorems we have to memorize.
I think I have found a pretty intuitive way to think about the ...
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1answer
41 views
Prove that the integral of a differential form is zero
Let $\mathbb{X}$ and $\mathbb{Y}$ be vector fields on $\mathbb{R}^n$ such that $[\mathbb{X},\mathbb{Y}]=0$, and let $\Phi_t$ and $\Psi_s$ denote their respective flows. Let $c:[0,1]\times [0,1]\to \...
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2answers
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Application of Stokes' Theorem with the vector field $K=(-zy,zx,z^2)$ and the surface $-2 \leq z \leq 1, \sqrt{x^2+y^2}=1+z^2$
I'm asked to evaluate the flux $$\int_{S} rot K d\omega,$$ where $S$ is the region $-2 \leq z \leq 1, \sqrt{x^2+y^2}=1+z^2$ and $K$ is the vector field $(-zy,zx,z^2)$.
So when I evaluate directly the ...
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Apparent paradox when we use the Kelvin–Stokes theorem and there is a time dependency
I am having trouble to understand what is going on with the Maxwell–Faraday equation:
$$\nabla \times E = - \frac{\partial B}{\partial t},$$
where $E$ is the electric firld and $B$ the magnetic field. ...
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1answer
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What goes wrong with Stokes theorem if a surface is not orientable?
For the Möbius strip parametrized by $\{\sigma(\theta,r)=((1+r\sin(\theta/2))\cos\theta,(1+r\sin(\theta/2))\sin\theta,r\cos(\theta/2))\ \mid \\ (\theta,r)\in A=(0,2\pi)\times(-1/2,1/2) \}$
we get ...
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1answer
113 views
Verify Stokes' theorem on a hemisphere using a line integral
When solving this question, I wrote $r(t)$ as $\langle\cos t,0,\sin t\rangle$ then I differentiated it and got $dr=\langle-\sin t,0,\cos t\rangle\,dt$, then i substituted in the formula for line ...
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1answer
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Determining $R$ so that the flux of the F field through S is maximum
For any $R>0$ let the surface $S={(x,y,z):x^2+y^2+(z-1)^2 = R^2; z≥1}$ oriented with the normal whose third coordinate is positive. And let the field $F(x,y,z) = (zx-x cos (z), -zy+ y cos(z), 4-x^...
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1answer
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Where is my mistake? Calculating surface integral/Stoke's theorem
Let
$F(x,y,z)= \begin{pmatrix} -y \\ 2x\\z \end{pmatrix}$
be a vector field and $A$ a hemisphere
with $x^2+y^2+z^2=9 $ , $ z>0 $
with a circular edge at the $x,y $- level with the unit normal ...
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1answer
52 views
Volume form on a compact manifold is not exact
I am trying to show that a volume form $\mu$ on a compact manifold $M$ is not exact, i.e. show there is no $\alpha \in \Omega^{n-1}(M)$ such that $d\alpha = \mu$.
My attempt is the following: Suppose,...
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0answers
51 views
Intuition on Stokes' Theorem
Stokes' Theorem says that $$\int_C\vec{F} \cdot d\vec{r} = \int
\int_S (curl \space\vec{F}) \space\cdot \vec{n} \space dS$$
I understand that $curl \space\vec{F}$ is the "spin" or "circulation" on a ...
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Integration of a (0,1)-form on the boundary of a Riemann surface
In Simon Donaldson's book, he says that for any (0,1)-form $\theta$ on a compact connected Riemann surface $X$, the integral of $\partial\theta$ over $X$ is zero by Stokes' theorem - but that seems ...
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1answer
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Stokes' Theorem - Vector Field
I am having problems trying to verify Stokes' theorem (below) as part of a question.
$$\iint_{S} \text{curl} \vec F \cdot d\vec S=\oint_{c} \vec F \cdot d\vec r$$
The vector field in question is $\...
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0answers
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Frightening Stokes Theorem Computation
I came across a rather frightening problem in my problem set and I am confused about it.
I need to compute the flux of a field $\vec F = \langle y, x^2, z(x^2-y^3)^7 \cos(e^{xyz}) \rangle$ through ...
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1answer
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Using Stokes's Theorem to Compute the Circulation of a Vector Field over a Triangle in the Plane
I'm tasked with computing the circulation of the vector field $\vec F = <y^2, z, xy>$ along the triangle with vertices $(1,0,0), (0,1,0), (0,0,1)$ with the orientation of the curve following ...
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1answer
46 views
calculate the surface integral in the upper hemisphere
Calculate the surface integral $f(x,y,z)=x^2+y^2+z^2$ in the upper hemisphere of the sphere $x^2+y^2+(z-1)^2=1$
I tried to compute the value of the surface integral $\iint_S{F.n} dS$ with the ...
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0answers
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Gauss-bonnet just for geodesic triangles
I have a question about some ways for proving the Gauss-Bonnet theorem just for small geodesic triangles. The general formula for the Gauss-Bonnet theorem is
$$\iint_R KdS+\sum_{i=0}^k\int_{s_i}^{s_{i+...
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Solve the following integral using Stokes Theorem.
I am asked to evaluate the following integral:
$$\int\int \text{curl} \ \vec{F} \cdot d\vec{S}$$
where $F = (y,-x,zx^3y^2)$ and $S$ is the surface given by $x^2 + y^2 + 3z^2 = 1$ with $z \leq 0$.
I ...
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3answers
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No where vanishing exact $1$-form on compact manifold.
I found several answers on the following question :
Does there exists a no where vanishing exact $1$-form on a compact manifold without boundary?
All answer says that certainly not. But I cannot ...
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1answer
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How do I use Stokes' theorem to find curl
How do I solve questions that ask me to use Stokes' Theorem to find curl F
For example:
Use Stoke's Theorem to find curl F:
$$F(x, y, z) = \langle e^x+y^2, y^2+z^2, \sin(z)+x^2\rangle$$
$\iint_S ...
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1answer
63 views
Differential Forms and Applications by do Carmo - Divergence theorem
I read the proof of Stokes theorem for manifolds by do Carmo's book and I'm trying understand an example (the Divergence theorem) given after the proof of Stoke's theorem, but I didn't understand. A ...
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1answer
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Why is curl considered the differential operator in 3-space?
Why is the curl considered the differential operator in 3-space instead of the gradient? It would seem that the gradient is the corollary to the derivative in 2-space when extending to 3-space. This ...
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1answer
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Orientation in the proof of Stokes Theorem
I'm reading the proof of Stokes theorem at page 83 of "Godinho, Natàrio, An introduction to Riemannian geometry" and I can't understand a passage in it, probably because the definition of ...
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Stokes First Problem/Rayleigh with a wall separation of variables
like the title says, I would like to calculate Stokes first problem with a fixed wall at d. We have to do it with separation of variables. If I take the obvious Ansatz, $\lambda=0$ my time dependecy ...
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0answers
46 views
Understanding the Difference between vector and velocity fields
I'm having difficulty understanding the difference between a vector and velocity field. In particular, there are two questions which I had to complete which ask to find the flux of a velocity field. ...
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1answer
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Verifying Stokes' Theorem for an upper hemisphere
There is a hemisphere, radius $1$, centred at $(0,0,0)$, where the vector field
is $$\vec F = \Big(x^3+\frac{z^4}{4}\Big) \hat i + 4x \hat j + (xz^3+z^2) \hat k$$
Verify Stokes' theorem for this ...
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1answer
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Calculating Flux of a surface
I have to calculate the flux a surface but I don't really find the way to parametrize the surface. Moreover, I am not sure if I have to use Gauss theorem or Stoke's theorem.
This is my exercise :
...
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1answer
44 views
The proof of Riemann’s bilinear relations
I am reading the proof from http://page.math.tu-berlin.de/~bobenko/papers/2011_Bob.pdf
I am very confused the step: (from Stokes theorem)
$$\int_Rw\wedge w'=\int_{\partial F_g}w'(p)\int_{P_0}^Pw$$
...
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1answer
63 views
Using Stoke's Theorem on a 2D vector field?
So i'm supposed to calculate the line integral
$$\int_C\mathbf{F}\cdot d\mathbf{l}$$
where $\mathbf{F}=(xy^2+2y)\vec{\mathbf{x}}+(x^2y+2x)\vec{\mathbf{y}}$
Through curve $C_1$ which contains two ...
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0answers
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Clarifying Stokes' Theorem misconceptions with a problem
Question: Using Stokes's Theorem for $A=(y+z)\hat i-(xz) \hat j+(y^2)\hat k$ where $S$ is the surface of the region in the first octant bounded by $2x+z=6$ and $y=2$ which is not included in the (a) $...
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2answers
173 views
Verify Stokes' Theorem for $v=zi+xj+yk$ over the hemispherical surface $x^2+y^2+z^2=1$ and $z \gt 0$.
Verify Stokes theorem if $v=zi+xj+yk$ (where $i,j,k$ are the identity vectors for the $x,y,z$ axis) is taken over the hemispherical surface $x^2+y^2+z^2=1$ and $z \gt 0$.
Stokes theorem being:
$$\int\...
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0answers
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Help with Green's theorem
I am struggling doing a calculation with Green's theorem. I have to evaluate this integral
$ \int D \mathbf{r}^2 \nabla^2 p(\mathbf{r}, t) d \mathbf{r} $ ($ D$ is a numerical coefficient). Actually I ...
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2answers
28 views
Simple stokes - why is this the correct orientation?
We want to calculate $\iint_{S}\text{curl}(\vec F)dS$ where $\vec{F}(x,y,z)=(y^2z, xz,x^2y^2)$ and $S$ is the part of the paraboloid $z=x^2+y^2$ that's inside the cylinder $x^2+y^2= 1$ with an outward ...
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0answers
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Projection of the surface on another surface using Stokes theorem?
Can multiple surfaces connected together be used to project them onto another surface?
For example let's take a cube.
I have seen different examples from books where they project the upper surface ...
