Which of the following phenomena is the practical evidence for the existence of the continual motion of molecules?
Answer Details
The phenomenon that provides practical evidence for the existence of the continual motion of molecules is Brownian motion.
Brownian motion is the random and erratic motion of small particles in a fluid (such as water) that are visible under a microscope. This motion is caused by the collision of the particles with the much smaller molecules of the fluid, which are constantly in motion due to their thermal energy.
The erratic motion of the particles in Brownian motion provides evidence for the continual motion of molecules, since the collisions between the particles and the fluid molecules are a direct result of the continual motion of the fluid molecules. This motion is caused by the thermal energy of the fluid molecules, which is a form of kinetic energy.
In contrast, translational motion refers to the linear motion of an object in space, rotational motion refers to the circular motion of an object around an axis, and oscillatory motion refers to the repetitive back-and-forth motion of an object around a fixed position. While these types of motion are also a result of the kinetic energy of molecules, they do not provide direct evidence for the continual motion of molecules in the same way that Brownian motion does.