Center of mass rigid body, the gravity forces will not cause the body to rotate, which means the weight of the body can be considered to be concentrated at the center of mass. The linear and angular momentum of a collection of particles can be simplified by measuring the position and velocity of the particles relative to the center of mass. Let the system of particles "P", "i"=1...,"n" of masses "m" be located at the coordinates r with velocities v. Select a reference point R and compute the relative position and velocity vectors, The total linear and angular momentum vectors relative to the
Front velocity any medium tends to one as the frequency tends to infinity, that the wave discontinuity, called the "front", propagates at a speed less than or equal to the speed of light "c" in any medium. In fact, the earliest appearance of the front of an electromagnetic disturbance (the precursor) travels at the "front velocity", which is "c", "no matter what the medium". However, the process always starts from zero amplitude and builds up. Front velocity In physics, front velocity is the speed at which the first rise of a pulse above zero moves forward. In mathematics, it is used to