3) An air conditioning unit of mass 1500kg is placed in the middle of an 8m long simply supported beam (EI = 6 x 103kNm2) of negligible mass. The motor runs at 300RPM and produces an unbalanced load of 100kg. Assuming a damping ratio of 10%, determine the steady-state amplitude and deflection at the midpoint?. (What rpm will result in resonance, and what is the associated deflection