218 PRACTICAL MATHEMATICS 



Total moment = - \ y z dx 

 2 Jz 



f 



J 



2n doj 



2 

 2-273 2 



Then y = 



2 x 3-274 



66-24 



66-24 



(43.274 _ 23-274 \ 



15-92 

 = 4-160 



(2) For the area B, and taking horizontal strips each of 

 breadth 8*/. 



Moment of strip == any y 



pii 

 Total moment = I xy dy 



J 5 



dx 



f 

 = na 2 \ 



J 



na 



Then y = 



1-137 X 2-273 2 



3-274 ; 



= 150-7 

 150-7 



18-08 

 = 8-335 



Taking vertical strips each of breadth $x, 

 Moment of strip = (11 y)x Bx 



Total moment of area PQS =1 (11 - y}x dx 



Jz 



f4 f4 



= 11 xdxa\ x n+1 dx 

 Jz Jz 



1 ' ' - - ' pn+2 



J 5 



