Entropic approach to Brownian movement
Abstract
A diffusional driving force, called the radial force, which is responsible for the increase with time of the scalar separation between a fixed point and a particle undergoing threedimensional Brownian motion, is derived using Boltzmann's equation. The radial force is used to derive several results from the classical theory of Brownian motion, namely Einstein's <x^{2}> = 2Dt equation and the expression for the onedimensional harmonic oscillator. The radial force concept is then extended to establish a thermodynamic criterion for the occurrence of a melting transition in a liquid whose particles attract one another by means of centrally symmetric forces. The theory, when applied to the alkali halide and alkalineearth oxide molten salts, accurately predicts the observed melting temperatures. The definition of the dielectric constant used in the ionic salt fusion theory also provides a basis for understanding molten salt surface tensions. Finally, the radial force is used to demonstrate that an ideal rubber network is not prone to collapse into a state having zero volume.
 Publication:

American Journal of Physics
 Pub Date:
 May 1980
 DOI:
 10.1119/1.12095
 Bibcode:
 1980AmJPh..48..354N
 Keywords:

 05.40.+j