Which of the following is NOT a degree of motion associated with rotary-wing aircraft?

Bank is not a degree of motion associated with rotary-wing aircraft. In the context of rotary-wing flight, the primary degrees of motion are pitch, roll, and yaw.

Pitch refers to the up or down angle of the aircraft’s nose, which affects altitude and descent. Roll refers to the tilt of the helicopter’s body from side to side, which is crucial for turning and changing lateral direction. Yaw involves the horizontal rotation around the vertical axis, influencing the direction the aircraft is facing.

In fixed-wing aircraft, bank is commonly used to describe the aircraft's angle when turning; however, in rotary-wing aviation, the concept of banking is typically encompassed within the actions of roll and yaw. Therefore, bank is not a standalone motion in the same context as the other three. This distinction is important for understanding the control and maneuverability of rotary-wing aircraft.