Question

4. An engine connecting rod is 25 cm between the centre-lines of the big and small ends. The big end bearing is 5 cm diameter and the small end is 2.5 cm diameter. When the connecting rod is suspended on a horizontal knife edge about its big end and vibrated as a compound pendulum, the measured frequency of vibration is 1.145 Hz. When the experiment is repeated with the rod suspended from the small end, the measured frequency of vibration is 1.082 Hz. Determine the position of the centre of mass G and the radius of gyration kG about G. Ans. G is 0.1 m from the centre of the big end. kG = 0.09 m