The frame shown consists of a steel beam welded rigidly to two vertical channels . An eccentric exciter weighing 350 N is attached to the beam , which weighs 15 KN and is used to excite the frame . The unbalance weight of the exciter is 30 N and it has an eccentricity of 7 cm . By varying the rotational speed of the exciter until resonance occurs , the maximum horizontal amplitude was found to be 5 mm . Assuming no bending on the beam and considering the channels to be completely fixed at C and D ( see Figure ( 1 ) ) , determine , ( a ) The natural frequency in Hz . ( b ) The damping factor . ( c ) The magnification factor at resonance . ( d ) Discuss whether this values in ( a ) , ( b ) and ( c ) are better for the structure if it is high or low .