Please help!! Thank you so much! (I hate school) :,)

Let f(x,y,z) = ztan-1(y2) i + z3ln(x2 + 1) j + z k. find the flux of f across the part of the paraboloid x2 + y2 + z = 3 that li

Sophie [7]

Consider the closed region $V$ bounded simultaneously by the paraboloid and plane, jointly denoted $S$ . By the divergence theorem,

$\displaystyle\iint_S\mathbf f(x,y,z)\cdot\mathrm dS=\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV$

And since we have

$\nabla\cdot\mathbf f(x,y,z)=1$

the volume integral will be much easier to compute. Converting to cylindrical coordinates, we have

$\displaystyle\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV=\iiint_V\mathrm dV$
$=\displaystyle\int_{\theta=0}^{\theta=2\pi}\int_{r=0}^{r=1}\int_{z=2}^{z=3-r^2}r\,\mathrm dz\,\mathrm dr\,\mathrm d\theta$
$=\displaystyle2\pi\int_{r=0}^{r=1}r(3-r^2-2)\,\mathrm dr$
$=\dfrac\pi2$

Then the integral over the paraboloid would be the difference of the integral over the total surface and the integral over the disk. Denoting the disk by $D$ , we have

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-\iint_D\mathbf f\cdot\mathrm dS$

Parameterize $D$ by

$\mathbf s(u,v)=u\cos v\,\mathbf i+u\sin v\,\mathbf j+2\,\mathbf k$
$\implies\mathbf s_u\times\mathbf s_v=u\,\mathbf k$

which would give a unit normal vector of $\mathbf k$ . However, the divergence theorem requires that the closed surface $S$ be oriented with outward-pointing normal vectors, which means we should instead use $\mathbf s_v\times\mathbf s_u=-u\,\mathbf k$ .

Now,

$\displaystyle\iint_D\mathbf f\cdot\mathrm dS=\int_{u=0}^{u=1}\int_{v=0}^{v=2\pi}\mathbf f(x(u,v),y(u,v),z(u,v))\cdot(-u\,\mathbf k)\,\mathrm dv\,\mathrm du$
$=\displaystyle-4\pi\int_{u=0}^{u=1}u\,\mathrm du$
$=-2\pi$

So, the flux over the paraboloid alone is

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-(-2\pi)=\dfrac{5\pi}2$

6 0

3 years ago

Easy 10 points and brainliest :)

Snezhnost [94]

Answer:

quadrant 1

Step-by-step explanation:

both of them are positive

8 0

3 years ago

Read 2 more answers

the ortiz will travel fron indianapolis to denver this summer.The driving distance between the two cities is 1058 miles. They ne

Sladkaya [172]

Answer:

a. 2116 miles

b. 105.8 gallons

c. $305.76

d. cost per gallon = total cost / number of gallons = total cost/105.8

Step-by-step explanation:

The round-trip distance is the sum of the distances there and back. It is double the one-way distance.

round-trip distance = 2 × one-way distance

round-trip distance = 2 × 1058 miles = 2116 miles

__

The gas used will be the distance divided by miles per gallon.

gas used = round-trip distance / miles-per-gallon

gas used = (2116 mi)/(20 mi/gal) = 105.8 gal

__

The cost of gas will be the product of cost per gallon and number of gallons.

cost of gas = cost-per-gallon × gallons

cost of gas = $2.89/gal × 105.8 gal = $305.762 ≈ $305.76

__

The relation used in the previous step can be used to find the cost per gallon. Divide that equation by gallons to get ...

(cost of gas)/gallons = cost-per-gallon

For the same trip, the number of gallons is 105.8, so the equation becomes ...

cost-per-gallon = (cost of gas)/105.8

3 0

1 year ago

The claim is that the white blood cell counts of adult females are normally distributed, with a standard deviation equal to 1.6

maxonik [38]

Answer:

78.46

Step-by-step explanation:

Given that

Pop. Standard deviation = 1.61

Sample standard deviation = 2.15

Sample mean = 7.47

Sample size = 45

Recall that

Test stat for chi square

= (n - 1) (sample standard dev/pop standard dev)^2

= 45 - 1 (2.15/1.61)^2

= 44(1.3354)^2

= 44 × 1.78329

= 78.46

4 0

3 years ago

Read 2 more answers

What is the solution to -3x+5?

ziro4ka [17]

Answer:

x = 5/3

Step-by-step explanation:

-3x+5

-5= -3x

-5/-3 = 5/3

7 0

11 months ago