**Discussion**

The velocity of A is always tangent to the path of A, and the acceleration of A always points inward on the path of A, as expected.

In solving the problem, write the velocity and acceleration of A referenced to the motion of the center of disk, O. Point O travels on a straight path, so its velocity and acceleration are always in the horizontal direction. Note that for a standard *xy*-coordinate system with *x* positive to the right and *y* positive upward, the angular velocity and angular acceleration of the disk are in the -*z* direction.

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