(b) Figure Q5(a) shows a system of three masses m, m and m3, which is attached to a tightly extendable string with consistent tension T, fixed at both ends with m = m3 = m and m = 2m. The length of each string is such that 4 = l = l3 = l. Assuming the tension does not vary with transverse motion, (i) determine the stiffness influence matrix of this system, and, (ii) estimate the natural frequency of this system. [CO2/PO3/C4] (10 marks) mi X1 m2 X2 13 m3 Figure Q5(a)