Between a solid mass of 10 kg and floor, two slab of isolator, natural rubber and felt are kept in series as shown in Fi

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Between a solid mass of 10 kg and floor, two slab of
isolator, natural rubber and felt are kept in series as shown in
Figure Q1(b). The natural rubber slab has a stiffness of 3000 N/m
and an equivalent viscous damping coefficient of 112 Ns/m. The
felt slab has a stiffness of 12,500 N/m and an equivalent viscous
damping coefficient of 160 Ns/m. (i) Sketch the single degree of
freedom spring-mass-damper system (2 marks) (ii) Determine the
undamped and damped natural frequencies of the system in the
vertical direction. Neglect the mass of the isolator