- #1
shaiqbashir
- 106
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Hi guys!
well! in the following question i need to verify The Stoke's Theorem:
Q: Verify Stoke's theorem for
F=6zi +(2x+y)j -xk
where "S" is the upper half of the sphere [tex]x^2+y^2+z^2=1[/tex]
bounded by a closed curve "C" [tex]x^2+y^2+z^2=1[/tex] at z=0 plane.
Now here is the stoke's theorem:
[tex]\oint F.dr = \int\int (curl of F).n ds[/tex]
OKz so when i just solved this problem, i found:
Curl of F = 7j + 2k
and [tex]n=\bigtriangledown (x^2+y^2+z^2-1)= 2xi+2yj+2zk[/tex]
and then
(curl of F). n= 14y+4z
now i put it under the integral sign like :
[tex]\int\int (14y+4z)ds[/tex]
i put here the value of z as
[tex]z=\sqrt{1-x^2-y^2}[/tex]
[tex]\int\int [(14y+4(\sqrt{1-x^2-y^2})]ds[/tex]
now what i have done is this that i take
[tex]x=r\cos\theta[/tex]
[tex]y=r\sin\theta[/tex]
[tex]ds=rdrd\theta[/tex]
and i finally put it in the integral sign
[tex]\int\int [14r\sin\theta+4(\sqrt{1-r^2\cos^2\theta-r^2\sin^2\theta})]rdrd\theta[/tex]
where [tex]0 \leq r\leq 1[/tex]
[tex]0\leq \theta \leq 2\pi [/tex]
now when i solve it
i found its answer to be
[tex]\frac{8\pi}{3}[/tex]
but when i solved the left hand side of the stoke's theorem:
i.e.
[tex]\oint F.dr[/tex]
i found it that
[tex]\oint F.dr = 2\pi[/tex]
and the result is that
the stoke's theorem is not getting verified. please tell me where I am making mistake in this problem.
both sides should be equal to each other. but I am not getting both of them equal to each other . please help!
thanks in advance!
well! in the following question i need to verify The Stoke's Theorem:
Q: Verify Stoke's theorem for
F=6zi +(2x+y)j -xk
where "S" is the upper half of the sphere [tex]x^2+y^2+z^2=1[/tex]
bounded by a closed curve "C" [tex]x^2+y^2+z^2=1[/tex] at z=0 plane.
Now here is the stoke's theorem:
[tex]\oint F.dr = \int\int (curl of F).n ds[/tex]
OKz so when i just solved this problem, i found:
Curl of F = 7j + 2k
and [tex]n=\bigtriangledown (x^2+y^2+z^2-1)= 2xi+2yj+2zk[/tex]
and then
(curl of F). n= 14y+4z
now i put it under the integral sign like :
[tex]\int\int (14y+4z)ds[/tex]
i put here the value of z as
[tex]z=\sqrt{1-x^2-y^2}[/tex]
[tex]\int\int [(14y+4(\sqrt{1-x^2-y^2})]ds[/tex]
now what i have done is this that i take
[tex]x=r\cos\theta[/tex]
[tex]y=r\sin\theta[/tex]
[tex]ds=rdrd\theta[/tex]
and i finally put it in the integral sign
[tex]\int\int [14r\sin\theta+4(\sqrt{1-r^2\cos^2\theta-r^2\sin^2\theta})]rdrd\theta[/tex]
where [tex]0 \leq r\leq 1[/tex]
[tex]0\leq \theta \leq 2\pi [/tex]
now when i solve it
i found its answer to be
[tex]\frac{8\pi}{3}[/tex]
but when i solved the left hand side of the stoke's theorem:
i.e.
[tex]\oint F.dr[/tex]
i found it that
[tex]\oint F.dr = 2\pi[/tex]
and the result is that
the stoke's theorem is not getting verified. please tell me where I am making mistake in this problem.
both sides should be equal to each other. but I am not getting both of them equal to each other . please help!
thanks in advance!
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