3) A certain machine of mass 400 kg has a shaft that rotates at 1800 rpm. It is known that the machine shows
resonance at 1200 rpm. An absorber is to be mounted on top of the machine so that the amplitude of its
vibration response with the absorber mounted, within the range 1000-2000 rpm, is less than 50% of its static
response measured without the absorber. Here, by static response, we mean the response if the magnitude
of the dynamic force were applied statically. Design the absorber. That is find suitable values of absorber
mass and stiffness.
Hint: Firstly, aim to reduce the amplitude at one frequency, then check the situation at the other frequency. Do
this until you find a solution. If you do not think that there is a solution, state it with an acceptable arguments.