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
∫ 10∫ 1 −x0dydx= 2I7-36.
I=∫∫SF~·ˆendS=[∫∫OCDG+∫∫GF A 0+∫∫F ABE+∫∫BEDC+∫∫EDGF+∫∫ABC 0]
F~·ˆendSOn face 0CDG ˆen=−eˆ 1 , F~·ˆen=−x^2
x=0= 0, dS=dydzOn face GFA0 ˆen=−eˆ 2 , F~·ˆen=−y^2
y=0= 0, dS=dxdzOn face FABE eˆn=ˆe 1 , F~·eˆn=x^2
x=1= 1, dS=dydzOn face BEDC, ˆen=ˆe 2 , F~·ˆen=y^2
y=1= 1, dS=dxdzOn face EDGF, ˆen=ˆe 3 , F~·ˆen=z^2
z=1= 1, dS=dxdyOn face ABC0, ˆen=−ˆe 3 , F~·ˆen=−z^2
z=0= 0, dS=dxdyAdd the above surface integrals over each face and showI=∫∫SF~·ˆendS= 1+1+1 = 3I7-37.
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
yI=∫∫Sf(x,y,z)dS=∫ 30∫ 102(x+ 1)ydxdzy = 9I7-38. Method I Use cartesian coordinates
ˆen=xˆe 1 +yˆe 2 +zˆe 3
3dS
=dxdy
|ˆen·eˆ 3 |= 3dxdy
zF~·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