Try This Method(substitute your values)
Centripetal force = Mass X Velocity^2/ Radius
<span>F= mv^2/r </span>
<span>so 80.5 X 40^2/200 </span>
<span>=644N</span>
The Equivalent resistance is :

The solution is in attachment for solution ~
Convert 10mm to metres = 0.01m
Wave speed = frequency *wavelength
= 4Hz*0.01m
= 0.04 m/s
Hope this helps