The masses and radi of the earth and moon are m, r and mp, r respesctively. their centres are at distance d apart. the minimum velocity with which a particle of mass m should be projected from a point milway berween their centres so that it escapes to infinity is (m,+m (r +r) (a) 2-d nd 57. a thin rod of length l is bent to form a semicircle. the mas whar will be the gravitatiónal potential at th