Homework # 25 - Math 250
The problems on this homework must be done alone. The honor code is in effect.
First name: Last name:
1. Evaluate the flux integral \(\int\int_S \langle x, y, z\rangle \cdot \vec{N}dS\) where \(S\) is the surface \(z = 2 - x - y\) where \(0 \leq x \leq 1, 0 \leq y \leq 1\).
a. -2
b. -1
c. 0
d. 1
e. 2
2. Evaluate the surface integral \(\int\int_S \langle 3z, -4, y\rangle \cdot \vec{N}dS\) where \(S: x + y + z = 1\), \(x \geq 0\), \(y \geq 0\), \(z \geq 0\). (As is typical in this situation, S has the upward orientation.)
a. \(-\frac{1}{3}\)
b. \(-\frac{2}{3}\)
c. -1
d. \(-\frac{4}{3}\)
e. \(-\frac{5}{3}\)
3. Evaluate the surface integral \(\int\int_S \langle x, y, z\rangle \cdot \vec{N}dS\) where \(S\) is the unit sphere centered at the point (1, 2, 5).(As is typical in this situation, S has the outward orientation.)
a. \(2\pi\)
b. \(3\pi\)
c. \(4\pi\)
d. \(5\pi\)
e. \(6\pi\)
4. Say \(\vec{F}\) is the velocity field for the flow of any incompressible fluid (like liquid water), and S is any bounded closed surface with the outward orientation. Then what can we say about \(\int\int_S \vec{F} \cdot \vec{N}dS\)?
a. It's 0 because the divergence is 0 everywhere.
b. It's 0 because the curl is 0 everywhere.
c. It could be any value because all real numbers should be respected.
d. It's never 0 because it's never really over.
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