Lesson+29+&+30

**﻿Advancememt in Physics @ Dwight Englewood** **Director: Elise Burns** **TA: Sebastian Luhol**

== =^^^Click Me^^^ = = = =**Notes: **= Sound is a wave cause by the vibration of matter and can be heard through a //medium//. A medium is the material that it moves through that can be air, wood, and steel. for sound waves traveling through air and any fluid medium are called //longitudinal// because particles of the medium vibrate **parallel** to the direction that the sound wave moves. A sound wave is a repeating pattern of high-pressure and low-pressure regions moving through a medium, it is sometimes called a //pressure wave.//
 * What is sound? And what are the //natures// of sounds? **

Compressions: areas of high presseure Rarefactions: areas of love pressure.

** What are the properties of a sound wave? ** Frequency, how much per second abbreviated in Hertz ( Hz ). The period of a sound wave are the measurements of time between hig pressure point or low pressure points.The sensation of a frequency is called the pitch. A high pitch sound indicates a high frequency sound wave and a low pitch sound ndicates a low frequency sound wave. "The amount of energy that is transported past a given area of the medium per unit of time is the //intensity//."



infrasound: a sound below the frequency of hearing ultrasound: a sound above the frequeny of hearing pitch: the "sensation" of frequency consonant: sound wave that is decribed as pleasant when heard octave: what seperates sounds into a 2 to 1 ratio third: what seperates a 5 to 4 ratio

How do sounds behave? When two waves meet while traveling in the same medium it is called a //wave interference// changing the sape of the medium.

Constructive interference: when 2 identical upward waves meet trveling in different direction, the medium takes on the shape of a pulse with twice the amplitude. Destrutive interference: an upward pulse and a downward pulse that have the same shape meet traveling in opposite directions the medium will make the equilibrium shape.

Doppler Effect: soni boom, plane picture from class waves getting closer together.

Diffraction is the change of direction of waves as they pass through openings and obstacles. If the wave is smaller than the obstacle you may not notice a change in diretion. Refraction is a change in the direction of waves as they pass from one medium to another.