4. The 10 kg slender rod is pinned to a small roller that slides freely along the slot. If the rod is released from rest at 0=0°, determine the force on the roller when 0 = 45° Notes: In this case, the rod's center of mass should only displace vertically and the rod end A will, of course, move horizontally. In order to solve this problem, you will likely need to use both Newton's 2nd Law and 1.0 m Energy methods. Specifically, you may want to use conservation of energy to help you find the angular velocity at the angle shown.