Correct Answer - A::B::C::D
Let there are two stars `1` and `2` as shows below.
Let `P` is a points between `C_(1)` and `C_(2)` where gravitational field strength is zero or at `p` field strength due to star `1` is equal and opposite to the field strength due to star `2`. Hence,
`(GM)/(r_(1)^(2)) = (G(16 M))/(r_(2)^(2))` or `(r_(2))/(r_(1))= 4` also `r_(1) + r_(2) = 10 a`
`:. r_(2) = ((4)/(4 + 1)) (10 a) = 8 a` and `r_(1) = 2a` ltbegt Now, the body of mass `m` is projected from the surface of larger star towards the smaller one. Between `C_(2)` and `P` it is attracted towards `2` and between `C_(1)` and `p` it will be attracted towards `1`. Therefore , the body should be projected to just cross `p` because beyond that the partical is attracted towards the smaller star itself.
From conservation of machanical energy `(1)/(2) m upsilon_(min)^(2)` ltbr. `= Potential energy of the body at `P` - Potential energy at the surface of larger star.
`:. (1)/(2) m upsilon_(min)^(2) = [-(GMm)/(r_(1)) - (16 GMm)/(r_(2))] - [-(GMm)/(10 a - 2a) - (16 GMm)/(2a)]`
`=[-(GMm)/(2a) - (16 GMm)/(8a)] - [-(GMm)/(2a) - (16 GMm)/(a)]`
or `(1)/(2) m upsilon_(min)^(2) = ((45)/(8)) rArr :. upsilon_(min) = (3sqrt(5))/(2) (sqrt((GM)/(a)))`