Mechanics of a Macroscopic Particle
In de Broglie's relation, the particle nature is inversely related to its wave nature. For a macroscopic particle, which has a larger value of momentum, the wavelength as calculated from de Broglie relation is too small to be determined experimentally (see Example 1.13). For such a case, the wave nature may be completely ignored and thus the particle has only the corpuscular nature. The classical Newton's law of motion governs the motion of such a particle. If we know the position of a body at a particular instant, we can determine or calculate its position after some time if we know its velocity. Its movement can be represented by well-defined trajectories (or fixed paths).
Mechanics of a Sub-Atomic Particle
A sub-atomic particle (such as electron, proton, neutron, hydrogen atom, etc.) besides having the particle nature also has the significant wave nature. Its mechanics cannot be described by classical Newton's law of motion. The qualitative explanation, as proposed by Werner Heisenberg, may be understood from the following analysis: