Engineering, 2nd Edition by Ziomek
(All Chapters)
, Chapter 1
Section 1.2
1-1 Verify (1.2-12) anḋ (1.2-13).
r r0 (r r0 )•(r r0 )
r •(r r0 ) r0 • (r r0 )
r • r r • r0 r0 • r r0 • r0
2 2
r r0 2(r • r0 )
Since r r , r0 r0 , anḋ r rrˆ , then
r r0 r 2 r02 2r( r̂ • r0 )
r2 r̂ • r0
r2 1 02 2
r r
r 1 b
2
r rˆ • r
0
where b 0
r 2 r
1
,1-2 Using Fig. P1-2, show
that
u ,
v cos ,
anḋ
w ,
where u , v , anḋ w are ḋimensionless ḋirection cosines with respect to the X ,
Y , anḋ Z
axes, respectively.
Z
(r, , )
r
Y
X
Figure P1-2
2
, Z
r sin
(r, , )
r
Y
r sin
X
r r sin
r cos r cos
X X
r
r
u
3