The pressure exerted by gas is attributed to what phenomenon?

The pressure exerted by a gas is primarily attributed to the collisions between the gas molecules and the walls of their container. When gas molecules are in motion, they collide with each other and with the surfaces of the container. Each time a molecule strikes the surface, it exerts a force on that surface. The cumulative effect of countless molecular collisions results in what we measure as pressure.

As the gas molecules collide more frequently and with greater force, the pressure within the container increases. This relationship illustrates how pressure, volume, and temperature of a gas are interconnected, as described by the gas laws. For example, increasing the temperature of a gas typically leads to increased molecular speed, resulting in more frequent and forceful collisions, thereby increasing pressure.

In contrast, temperature changes, gas expansion, and fluid density contribute to different phenomena. Temperature changes affect kinetic energy and thus pressure indirectly, but they are not the direct cause of pressure. Gas expansion refers to the process where gas tends to occupy a larger volume, which can lead to pressure changes, but does not define what pressure is fundamentally. Fluid density relates to mass and volume, impacting buoyancy and other fluid dynamics rather than directly leading to pressure in a gas context.