a rod is attached to a disk at one end and to a collar at the other end; neglect the mass of the collar and the disk since they significantly smaller than the rod. Properties of the spring are given; note that the spring can move freely in the track to keep it aligned vertically. If the assembly starts from rest at theta $1$ before the force p is applied, determine the rod's angular velocity when the rod reaches a horizontal position. What is the minimal spring constant that would prevent the rod from reaching a horizontal position