g2HEY NUPUR , DONT WORRY , MAIN HOON NAA................
(KIDDING).....
NOW ,look...........
use conservation of energy ........
initial energy= -GM1 m/(d/2) -GM2 m/(d/2) + 1/2 m v2
( as mass m is d/2 apart from moon as well as earth , therefore , gravitational energy is there , and mass is given a velocity v , therefore kinetic energy is also present.....RIGHT)
NOW ,
FINAL ENERGY= -GM1 m/$ - GM2 m/$ ( $--- REPRESENTS INFINITY)
(THERE IS NO KINETIC ENERGY BCOZ AT THAT POINT V=0)
NOW EQUATING , WE GET
GM1m/ (d/2) + GM2 m/(d/2) = 1/2 m V2
now we get answer ----------------------- ( B)
RIGHT ..............IF RIGHT PLEASE GIVE SOME GRADES........................................ PLEASE...........
THANKU