Ch 11 - SOUND9th Science

Sound is a form of energy that produces a sensation of hearing.

It is strictly produced by the vibration (rapid to-and-fro motion) of objects.

Examples: Vibrating vocal cords in humans, a struck tuning fork, or a plucked rubber band.

Sound is a Mechanical Wave.

It strictly requires a material medium (solid, liquid, or gas) for propagation. The wave relies entirely on the physical interaction and collision of particles to pass the disturbance forward; without molecules (as in a vacuum), propagation is impossible.

In a Longitudinal Wave, the individual particles of the medium oscillate back and forth strictly parallel to the direction of wave propagation.

The particles themselves do not travel across the medium with the wave; they simply pass the physical disturbance to adjacent particles and return to their original mean position.