An early model of the atom, proposed by rutherford after his discovery of the atomic nucleus, had a positive point charge +ze (the nucleus) at the center of a sphere of radius r with uniformly distributed negative charge - ze. z is the atomic number, the number of protons in the nucleus and the number of electrons in the negative sphere. show that the electric field inside this atom is e_in = (ze/4πε//r^3))

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.