Work Step by Step
See the diagram. The arrow on the axis points west, the direction of the angular velocity. This is to the left. The linear velocity of a point on the top of the wheel is north, into the screen/page. If the angular acceleration points east, opposite the angular velocity, the wheel is slowing down and its angular speed is decreasing. This means that the tangential linear acceleration of a point on top of the wheel points opposite to its linear velocity, i.e., the tangential linear acceleration points south.