Three particles each of mass ‘M’ are kept at the vertices of an equilateral triangle of side ‘a’. A particle of mass ‘m’ is placed on one of the side at the midpoint. The force on ‘m’ is

Force on ‘m’ due to mass at A and C cancelled i .e  F1→=F2→    Force of attraction between two masses=G×Mmr2;universal gravitation constant=G; mass=m; distance=r;  Force on ‘m’ is only due to mass at ‘B’=F=G×MmBD2∴F=G×Mm32a2F=43a2×GMm