Consider a light rod of negligible mass and length L=8.1 m pivoted on a frictionless horizontal bearing at a point O. Attached to the end of the rod is a mass M1=2kg. Also, a second mass M2=2kg of equal size is attached to the rod (4/7 L from the lower end), as shown in the figure below. The acceleration of gravity is 9.8 m/s^2. What is the period of this pendulum in the small angle approximation? Answer in units of s.