Force needed to pull the string

[anand]

A mass M whirls around on a string which passes through a ring .Neglect gravity.Initially the mass is distance Ro from the center and is revolving at angular velocity Wo.The string is pulled with constant velocity V starting at t=0 so that the radial distance to the mass decreases.Draw a force diagram and obtain a differential equation for W.Find
(1) W(t)
(2) the force needed to pull the string

 

[mezarashi]

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