  We consider a space with noncommutativity of coordinates and noncommutativity
of momenta. It is shown that coordinates in noncommutative phase space depend
on mass therefore they can not be considered as kinematic variables. Also,
noncommutative momenta are not proportional to a mass as it has to be. We find
conditions on the parameters of noncommutativity on which these problems are
solved. It is important that on the same conditions the weak equivalence
principle is not violated, the properties of kinetic energy are recovered, and
the motion of the center-of-mass of composite system and relative motion are
independent in noncommutative phase space.
