The collar of mass m shown in Figure 1 slides up the vertical shaft under the action of a force F of constant magnitude but variable direction such that 0 = kt, where k is a constant and t is in seconds. The collar starts from rest with 0 = 0. The coefficient of kinetic friction between the collar and the shaft is k- Determine an expression for the magnitude F of the force that will result in the collar coming to rest as 0 approaches. Mk m. Figure 1: Sliding collar.