56. the masses and radii of the earth and moon are m,, r and m2, r2 respectively. their centres are at distance d apart. the minimum velocity with which a particle of mass m should be projected from a point midway between their centres so that it escapes to infinity is: (a) 2d (m, + m2) (b) 2 d cmt gm (m, +m2) (r, +r2) (d) 2, g (m +m,) 62. (e) 2, m,+m2)