Sound Waves

1. Speed of Sound Waves

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

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

4. 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)

5. Textbook Equation
B
v
ρ
=

6. Question 1: Find the speed of sound in
air at 200
C.
p = 1.2 kg/m3
B = 1.01 x 105
Pa
(From the
textbook)
V= sqrt(1.01x 105
/1.2) = 343m/s

7. Question 2: What is the
velocity of sound in air on a
day when the temperature is
equal to 270
C?
We know that speed at 200
C = 343 m/s
V= 343 x sqrt(Final temp/Initial temp)
= 343 x sqrt(300/293) = 347 m/s