To my understanding, it will oscillate back and forth in accordance with the frequency of the AC supply.
A DC motor is made in such a manner such that the split ring commutator reverses the flow of current every half a revolution (and ensure a constant direction of rotation). AC current reverses it's direction periodically regardless. So as the AC current direction changes, the split ring commutator would reciprocate the direction - meaning that a constant direction of current is maintained. Momentum of the coil should keep it moving in a certain direction untill the AC current changes direction.