302 
-2- 
The pressure at P due to this element is thus 
p= 0 tic ach ee 
et eS) 
= t-re-r r 
Digest) tox ie tan) 
r cy Co ca co 
The total pressure at P will be the integrated effect of all the elemental sources. until some 
time to there will be no effect at P. at any instant after this time all the elements do not 
necessarily contribute to the pressure at P. tet the effective elements lie between , and 1., 
2 
where ry and 1, are the roots of 
EAA ey cae ot 
ee C5 
Then for this condition the pressure at P is 
) 
ax 
= fei SPC 
p=) as cy 4 
y 
After some later time t the whole line will be contributory at P and the limits of integration 
will be 2L and 0 respectively where 2L is the total length of charge. 
r 
c 
Special Cases. 
Some particular cases of line charges will now be considered, In all these cases the 
function for pressure has been assumed as 
= —kt 
Pit) epee 
and the total length of line is 2L. 
Rectilinear Charges 
Case 1 Pon the perpendicular oisector of OL. (Figure 1b). 
The first effect at P is produced by the element at xX where XP is norma) to the wave front 
at P and 
sin@ = “2 
eh 
For this case _L-d tan@ d sec @ where d (e Wite distance of P from the 
Sinan Sa nearest point of the charge 
4 25 
ize (2 + a2)4 
t i= + a 
1 2 
The values of 1, and 1,-are given respectively 
c [ 2 2 A pe a 
Le, — tcS = bce? ot (ef opt] tort <tet 
= eal i 2 2 1 i 2 ° 1 
\ Ge ks | + 
1 2 
with the conditions that Ie, 7 0 
1, 7% a 
WHEN ..eeee 
