Find the tension in the horizontal string PQ and the string QR in the given figure. [Take `g=10m//s^(2)`]

Explanation

We may take the components and redraw it as

From figure, we get
`T_(1) sin 30^(@)=70N`
`therefore ` By Lami's theorem, `(T_(1))/(sin90^(@))=(T_(2))/(sin120^(@))=(W)/(sin150^(@))`
and `T_(2)=T_(1)cos30^(@)`
`therefore T_(1)=140N`
and `T_(2)=140 xx (sqrt(3))/(2)=70 sqrt(3)N`
Alternate method:
As `vecT_(1)+vecT_(2)+vecW=vec0`
`therefore` By Lami's theorem `(T_(1))/(sin90^(@))=(T_(2))/(sin120^(@))=(W)/(sin150^(@))`

`rArr T_(1)=(W sin90^(@))/(sin150^(@))=2W=2xx7xx10=140N`
and `T_(2)=(W sin 120^(@))/(sin150^(@))=(W xx(sqrt(3))/(2))/((1)/(2)) = 10xx7xx sqrt(3)=70 sqrt(3)N`