I7-34. (a)x,y-plane, coordinate curves~r(u 0 ,v)vertical lines,~r(u,v 0 )horizontal lines
(b) x,y-plane polar coordinates,~r(u 0 ,v) circles of radius u 0 ,~r(u,v 0 ) rays at
anglev 0.
I7-35. I= 4
∫ 1
0
∫ 1 −x
0
dydx= 2
I7-36.
I=
∫∫
S
F~·ˆendS=
[∫∫
OCDG
+
∫∫
GF A 0
+
∫∫
F ABE
+
∫∫
BEDC
+
∫∫
EDGF
+
∫∫
ABC 0
]
F~·ˆendS
On face 0CDG ˆen=−eˆ 1 , F~·ˆen=−x^2
x=0
= 0, dS=dydz
On face GFA0 ˆen=−eˆ 2 , F~·ˆen=−y^2
y=0
= 0, dS=dxdz
On face FABE eˆn=ˆe 1 , F~·eˆn=x^2
x=1
= 1, dS=dydz
On face BEDC, ˆen=ˆe 2 , F~·ˆen=y^2
y=1
= 1, dS=dxdz
On face EDGF, ˆen=ˆe 3 , F~·ˆen=z^2
z=1
= 1, dS=dxdy
On face ABC0, ˆen=−ˆe 3 , F~·ˆen=−z^2
z=0
= 0, dS=dxdy
Add the above surface integrals over each face and showI=
∫∫
S
F~·ˆendS= 1+1+1 = 3
I7-37.
φ=x^2 +y^2 −1 = 0, 0 ≤z≤ 3 , N~ = gradφ= 2xˆe 1 + 2yeˆ 2
eˆn=xˆe 1 +yeˆ 2 sincex^2 +y^2 = 1, dS= dxdz
|ˆen·ˆe 2 |
=dxdz
y
I=
∫∫
S
f(x,y,z)dS=
∫ 3
0
∫ 1
0
2(x+ 1)ydxdzy = 9
I7-38. Method I Use cartesian coordinates
ˆen=x
ˆe 1 +yˆe 2 +zˆe 3
3
dS
=
dxdy
|ˆen·eˆ 3 |
= 3dxdy
z
F~·ˆen=x(x+z) +y(y+z)−(x+y)z
3
=x
(^2) +y 2
3
I=
∫∫
S
F~·ˆendS=
∫ 3
− 3
∫+√ 9 −x 2
y=−√ 9 −x^2
√x^2 +y^2
9 −x^2 −y^2
dydx= 36π
Solutions Chapter 7