EXAMPLES. 



the preceding A 



usual 



ies, but par* 

 convcn 



(1) A revolves round a tangent line through an 



c of 180*; find the centre of gravity of the solid generated. 

 Lei Oy be the tangent line about which the circle revolves, 

 lie paper bisect the solid ; the centre of 

 gravity will axis of 



figure PQqp will W 



its n generate a semi-cylin.lru-nl shell, whose volume 



is ultimately tyirx&r ; the centre of gravity of this shell will 



** / 

 be in the axis of x at a distance from (see 



0; 



fore 



W i' ') 



1 be found that * -. 



-TT 



