ABSTRACT
E2.1. Kinematics Kinematics is the field of mechanics where the geometric properties of motion of a point or a rigid body are studied independently of their mass and causes of their motion.
E2.1.1. Kinematics of a Point To specify the motion of a point M is to introduce a rule determining the point position with respect to a reference frame Oxyz at each time instant. The most routine and convenient methods for specifying the motion of a point are the vector, coordinate, and natural methods. ◮ The vector method for specifying the motion of a point. In this method, the position of pointM is specified by the position vector r(t) drawn to this point from a stationary center (pole, point). For the pole one can take any point, for example, the origin O of a coordinate system (Fig. E2.1). The position vector is a vector function of a scalar argument-time tand in the course of time the endpoint of the vector r traces a curve in space, which is called the trajectory (or path) of the point.
