(1) A rigid bar (OA)with mass m and length L is simply supported at one end and free at the other end .A lumped mass M fixed at the end of A is subjected to a vertical harmonic excitation f(t). Two springs (k) are connected at the length a and b of the bar. Please calculate the natural frequency and response vibration of the system. (Figure 1) Note: m=10kg, L=1 m, a=0.25m, b=0.5m, k-5000N/m, M=50kg, f(t)=FcosQt (F=500N, Q=1000rpm). The vibration is very small. a b k L MA k m M Figure 1: Single Degree Vibration System f(t) A

A 2 DOF mass-spring system shown below with n = 1, k = 8, and m initial conditions 2₁ (0) = 1, 2₂(0) = 0, ₁ (0) = 0, and ₂(0) = 1. (a) Find the natural frequencies and normalized modal matrix [X] for the system. T x₁ (1) (b) Using modal analysis and the Cartesian solution form, find the free vibration re- sponse of the system x₁(t) and x2(t). Ţ x2₂ (1) www. 00000 = m m₁ = 00000 k₁ = k 00000 k₂ = nk m₂ = m k3= k = 2 DOF mass-spring system. 2 with the

A cantilever is driven in flexural vibration by an electrical coil mounted at its free end and moving in the field of a magnet. The coil has been so designed that its mass is sufficiently small that it may be neglected but unfortunately this resulted in the moment of inertia of the coil being by no means negligible. For the beam, Young's modulus is E, the density is p its length is I and the second moment of inertia is I. The moment of inertia of the coil about an axis through its centre of gravity (which coincides with the end of the beam) perpendicular to the plane of vibration is J. Determine the frequency equation for this system.

For the system below, the mass, m is attached to the end of a cantilever beam of length, l, elasticity, E, and moment of inertia, I. Derive the equation of motions and find the natural frequencies in two cases by lagrange energy method    a) k1=k2=0 b) k1≠k2≠0