A disc is free to rotate about a smooth horizontal axis passing through its centre of mass. A particle is fixed at the top of the disc. A slight push is given to the disc and it starts rotating. During the process.
A. only mechanical energy is conserved
B. only angular momentum (about the axis of rotation) is conserved
C. both mechanical energy and angular momentum are conserved
D. Neither the mechanical energy nor the angular momentum are conserved.
