Objectives What is sound? What physical properties of a medium affect the speed at which sound travels through it?
What is a Sound Wave? Sound waves carry energy through a medium without the particles of the medium traveling along.
What is the medium through which sound waves travel?
What is a Sound? Sound is a disturbance that travels through a medium as a longitudinal wave.
How are sound waves made? Air is made up of tiny particles Vibrations generate a disturbance in the molecules in the air The force of the disturbance pushes the molecules closer together generating a compression In between vibrations, the molecules spread out and rarefactions are created.
The speed of sound in different media: The speed of sound depends on the physical properties of the medium it travels through. Air at room temperature – 342 m/s The speed sound can travel through a medium depends on: –Elasticity –Density –Temperature
Elasticity – the ability of a material to bounce back after being disturbed Speed depends on how well the particles in the medium bounce back after being disturbed The more elastic, the faster sound travels Examples: –Solids are more elastic than liquids –Gases are not very elastic at all
Density Density – how much matter, or mass, there is in a given amount of space or volume The speed of sound depends on how close together the particles of the substance are.
Density Continued Sound travels more slowly in denser mediums More dense means more mass per volume The particles of a dense material do not move as quickly as those of a less dense material
Temperature Sound travels more slowly at lower temperatures than at higher temperatures At low temperatures, the particles of a medium are sluggish Sound waves move and return to their original positions more slowly than they would at high temperatures.