For the two-mass system in Fig. P8.1, derive the equations of motion, and write the equations in matrix form, 

(a) Let coordinate u i be the absolute motion of mass 1, and let coordinate u2 be the absolute motion of mass 2. 

(b) Let coordinate u, be the absolute motion of mass 1, and let coordinate u2 be the motion of mass 2 relative to mass 1. 

(c) Discuss briefly how your answer to part 

(d) differs from your answer to part (a).