300 mm 4. (20 pts) If the position of the 3-kg collar C on the smooth rod AB is held at r-720 mm, when the mechanism is rotating about the vertical axis with the constant angular velocity w. The spring has stretched length of 400 mm. Neglect the mass of the rod and the size of the collar. a) Draw free-body and kinetic diagrams of the collar. b) Find the force on the spring. c) Determine the constant angular velocity w. d) What is the normal force between the collar C and the rod AB. W wwwwwwww =200 N/m B C