A mass m is attached at one end of a rigid rod of length `, and the rod is suspended at its other hand by a frictionless pivot as illustrated in the

A mass m is attached at one end of a rigid rod of length `, and the rod is suspended at its other hand by a frictionless pivot as illustrated in the figure. The rod is released from rest at an angle α0 < π/2 with the vertical.

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(i) (3 points) Using the conservation of energy to find the angle α as a function of time.

(ii) (3 points) At what angle α does the force in the rod change from compression to tension?