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2 years ago

Plz help it's due tomorrow

Mathematics

1 answer:

posledela2 years ago

7 0

Most of the answers are in the book. 1&2 is based on vocabulary and 8&9 are on the chart

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Evaluate the surface integral S F · dS for the given vector field F and the oriented surface S. In other words, find the flux of

tresset_1 [31]

Because I've gone ahead with trying to parameterize $S$ directly and learned the hard way that the resulting integral is large and annoying to work with, I'll propose a less direct approach.

Rather than compute the surface integral over $S$ straight away, let's close off the hemisphere with the disk $D$ of radius 9 centered at the origin and coincident with the plane $y=0$ . Then by the divergence theorem, since the region $S\cup D$ is closed, we have

$\displaystyle\iint_{S\cup D}\vec F\cdot\mathrm d\vec S=\iiint_R(\nabla\cdot\vec F)\,\mathrm dV$

where $R$ is the interior of $S\cup D$ . $\vec F$ has divergence

$\nabla\cdot\vec F(x,y,z)=\dfrac{\partial(xz)}{\partial x}+\dfrac{\partial(x)}{\partial y}+\dfrac{\partial(y)}{\partial z}=z$

so the flux over the closed region is

$\displaystyle\iiint_Rz\,\mathrm dV=\int_0^\pi\int_0^\pi\int_0^9\rho^3\cos\varphi\sin\varphi\,\mathrm d\rho\,\mathrm d\theta\,\mathrm d\varphi=0$

The total flux over the closed surface is equal to the flux over its component surfaces, so we have

$\displaystyle\iint_{S\cup D}\vec F\cdot\mathrm d\vec S=\iint_S\vec F\cdot\mathrm d\vec S+\iint_D\vec F\cdot\mathrm d\vec S=0$

$\implies\boxed{\displaystyle\iint_S\vec F\cdot\mathrm d\vec S=-\iint_D\vec F\cdot\mathrm d\vec S}$

Parameterize $D$ by

$\vec s(u,v)=u\cos v\,\vec\imath+u\sin v\,\vec k$

with $0\le u\le9$ and $0\le v\le2\pi$ . Take the normal vector to $D$ to be

$\vec s_u\times\vec s_v=-u\,\vec\jmath$

Then the flux of $\vec F$ across $S$ is

$\displaystyle\iint_D\vec F\cdot\mathrm d\vec S=\int_0^{2\pi}\int_0^9\vec F(x(u,v),y(u,v),z(u,v))\cdot(\vec s_u\times\vec s_v)\,\mathrm du\,\mathrm dv$

$=\displaystyle\int_0^{2\pi}\int_0^9(u^2\cos v\sin v\,\vec\imath+u\cos v\,\vec\jmath)\cdot(-u\,\vec\jmath)\,\mathrm du\,\mathrm dv$

$=\displaystyle-\int_0^{2\pi}\int_0^9u^2\cos v\,\mathrm du\,\mathrm dv=0$

$\implies\displaystyle\iint_S\vec F\cdot\mathrm d\vec S=\boxed{0}$

8 0

3 years ago

Complete the work shown to answer the question.

blagie [28]

Answer:

Since 7 and 11 are both rational, the sum and difference are rational.

Step-by-step explanation: It's A

5 0

2 years ago

Pls, help with this question

nikklg [1K]

Answer:

$m\text{ arc BC} =32\\m\angle 2=16\\m\angle3=74\\m\angle4=74\\m\angle5=16$

Step-by-step explanation:

Arc BC is the intercepted arc for the central angle COB, so its measure is the same as the central angle.

Angle 2 is an inscribed angle, so its measure is half the measure of the intercepted arc BC.

Angles 3 and 4 are congruent inside an isosceles triangle (OB = OC, both radii), and the sum of all angles in triangle COB is 180 degrees, so

180 - 32 = 148 (sum of angles 3 and 4)

Each of angles 3 and 4 measure half that remaining 148 degrees.

Angle 5 is one of two congruent angles in an isosceles triangle AOC (OA = OC) so its measure is that of angle 2.

4 0

2 years ago

Write the equation of the parabola that has the vertex at point (2,-11) and passes through the point (0,5).

aleksandr82 [10.1K]

$~~~~~~\textit{vertical parabola vertex form} \\\\ y=a(x- h)^2+ k\qquad \begin{cases} \stackrel{vertex}{(h,k)}\\\\ \stackrel{"a"~is~negative}{op ens~\cap}\qquad \stackrel{"a"~is~positive}{op ens~\cup} \end{cases} \\\\[-0.35em] \rule{34em}{0.25pt}$

$\stackrel{vertex}{(\stackrel{h}{2}~~,~~\stackrel{k}{-11})}\qquad y=a(x-2)^2-11\qquad \qquad \textit{we also know that} \begin{cases} x=0\\ y=5 \end{cases} \\\\\\ 5=a(0-2)^2-11\implies 16=4a\implies \cfrac{16}{4}=a\implies 4=a \\\\[-0.35em] ~\dotfill\\\\ ~\hfill y=4(x-2)^2-11~\hfill$

7 0

2 years ago

How to explain whats 4.5 ÷ 5 =

Lerok [7]

Answer:

0.9

Step-by-step explanation:

because if you multiply 0.9 by 5 it equals 4.5, why?

well 0.9 isn't a full number it's not even 1!

If you multiply

5 × 1 = 5

so if you multiply what's smaller than 1 by 5

5 × 0.9 = 4.5

Hope this helps!

Have a nice day!

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8 0

2 years ago