Kinematics
To describe motion, kinematics studies the paths of points, lines and other geometric objects in space, and some of their properties such as velocity and acceleration. Astrophysics uses kinematics to describe the motion of celestial bodies and systems. Mechanical engineering, robotics and biomechanics use it  to describe the motion of systems composed of joined parts  such as an engine, a robotic arm or the skeleton of the human body.