Physics – 2.1.2 Particle model | e-Consult

The random motion of particles in a suspension is a direct consequence of the kinetic theory of matter, which postulates that all matter is composed of particles in constant, random motion. The kinetic theory states that the average kinetic energy of the particles in a substance is directly proportional to the absolute temperature of the substance. This means that as the temperature increases, the particles move faster and their random motion becomes more vigorous.

The concept of collisions is central to the kinetic theory and is directly relevant to the observed random motion. As particles move randomly, they constantly collide with each other and with the walls of the container. These collisions cause the particles to change direction and speed, resulting in the erratic, unpredictable paths that we observe. The frequency of collisions is also dependent on the particle size and the density of the substance. Smaller particles experience more frequent collisions relative to their size, contributing to the overall random motion. The collisions are not perfectly elastic; some kinetic energy is lost to heat during each collision.