Rotating the trunk to the right is movement around the Y axis in:

Rotating the trunk to the right is a movement around the Y axis, and when considering the direction of the angle movement, this rotation is classified as negative in the context of right-hand rule axes.

In biomechanics and kinematics, rotation about the Y axis typically refers to movement that affects the body's transverse plane. When the trunk rotates to the right, it involves a clockwise motion when viewed from above, which is conventionally represented as a negative angle using the right-hand rule for three-dimensional space.

To clarify the axes:

• The Y axis runs vertically, and rotation around this axis would be like twisting.

• Positive rotations (like +θY) would indicate counterclockwise movements, while negative rotations (like −θY) denote clockwise movements.

Thus, when the trunk rotates to the right, it is indeed a negative rotation about the Y axis, making the designation of −θY correct. This understanding is essential in biomechanics for accurately describing and analyzing human movement in relation to body mechanics.