Origin on the body have a velocity

Origin on the body” refers to a coordinate system that is fixed to an aircraft or any other flying object. This coordinate system moves along with the object, allowing you to describe its motion from a perspective that’s centered on the object itself. This is particularly useful when analyzing the dynamics and kinematics of the object during flight.

• V0​ is the initial velocity vector.
• $u$ is the component of the vector in the $i$ (x) direction.
• $v$ is the component of the vector in the $j$ (y) direction.
• $w$ is the component of the vector in the $k$ (z) direction.