Correct Answer - `37^(@)`
`COLM : mv_(0) = (M + 2m) v_(1)`
`v_(1) = (mv_(0))/(m) = (v_(0))/(6) = 1 m//s`
`COME : rArr (1)/(2) (2m) ((v_(0))/(2))^(2) = (1)/(2) Mv_(1)^(2) + 2m xx g xx h + (1)/(2)(2m)v_(1)^(2)`
`rArr h = 0.3 m = L (1 - cos theta)`
`cos theta = 1 - (3)/(15) = (4)/(5) rArr 0 = 37^(@)`