The collar of mass \(m\) slides up the vertical shaft under the action of a force \(F\) of constant magnitude but variable direction. If \(\theta=k t\) where \(k\) is a constant and if the collar starts from rest with \(\theta=0\), determine the magnitude \(F\) of the force which will result in the collar coming to rest as \(\theta\) reaches \(\pi / 2\). The coefficient of kinetic friction between the collar and shaft is \(\mu_{k}\).

Transcribed Image Text:

m F MN F mg N