  We find condition on the parameters of noncommutativity on which a list of
important results can be obtained in a space with Lie-algebraic
noncommutativity. Namely, we show that the weak equivalence principle is
recovered in the space, the Poisson brackets for coordinates and momenta of the
center-of-mass of a composite system do not depend on its composition and
reproduce relations of noncommutative algebra for coordinates and momenta of
individual particles if parameters of noncommutativity corresponding to a
particle are proportional inversely to its mass. In addition in particular case
of Lie-algebraic noncommutativity (space coordinates commute to time) on this
condition the motion of the center-of-mass is independent of the relative
motion and problem of motion of the center-of-mass and problem corresponding to
the internal motion can be studied separately.
