Speed of Sound Waves

Objectives: To define sound and figure out how density affect its speed.

Definition of Sound: longitudinal mechanical wave that travels through an elastic medium.

Factors determining the Speed of Sound.

Sound waves have a wave speed dependent on elasticity and density.

A dense medium has lower wave speeds.

A medium that is more elastic springs back quicker and results in faster speeds (Bulk Modulus)

Textbook Equation

Bv

Question 1: Find the speed of sound in air at 200C. p = 1.2 kg/m3

B = 1.01 x 105 Pa (From the textbook)

V= sqrt(1.01x 105/1.2) = 343m/s

Question 2: What is the velocity of sound in air on a day when the temperature is equal to 270C?

We know that speed at 200C = 343 m/s

V= 343 x sqrt(Final temp/Initial temp)

= 343 x sqrt(300/293) = 347 m/s