Hvsrr.M or ITM.II>*. 



1ST 



a and a* be the angles - 



and I'b make 



! 

 nnd 



Now the pti i l.y II' in * 



!. and /' in i '. 1 lorces horizontally 



iw.llv, 



'/0 .... ..... (1), 



Pcoso+Pcosa- H'-O .......... (2); 



quntion of moments round C is an identical equation. 

 By (1), am a = sin a' and a - 



irr 



fore, by (2), -~ 2 cos a, 



which M the relation required. 



160. To find the ratio of the power and weight in a tyttem 

 " ;/* from a fixed point by a 



/M,'. .-';/////, Om /.//. injfot, n.'l in th> r ,i >'(>/ n 1 . -r i,' ./// 



other end on a fixed beam, and all the strings letng parallel. 

 ibcr of movcable pullies. 



I Let us neglect the weight of 

 pullies themselves. T 



tension of & a ir= 

 tension of a^\ = J : 



tension of a//, = .. M "; 



tension of 





and so on ; and the tension of the string 

 passing under the n* pully IT, and 

 this is equal to P\ therefore 



r 



- , , i ' 



