I am not a student. This is not a homework question. I am a 64 year old man who wants to understand a principle of physics. Suppose there is a large block of matter, designated as m2, which lies on a flat surface that initially is at rest. At some point in time a small block of matter, designated as m1, moves at an initial velocity vi and makes an inelastic collision with m2. I know from the conservation of linear momentum that the final momentum of the combined m1-m2 system must be equal to the initial momentum m1vi. What I am not sure of is what happens if there are 4 wheels attached to m2. Assume the moment of inertia of each wheel is 1/2 m3 r sq, where r is the radius of the wheel and m3 is the mass of each wheel. Suppose that m1 collides with the same initial velocity vi as before. Intuitively, it would seem that the translational momentum of the center of mass of the system would still be equal to the initial momentum m1vi per the conservation of linear momentum. But am I wrong and missing something having to do with overcoming the rotational inertia of the wheels?