1.3 Introduction
1.3.1 Characteristics of Sound - Pressure Variations
1.3.2 Characteristics of Sound - Speed of Sound
1.3,3 Characteristics of Sound - Pitch Loudness and Timbre
1.3.4 Characteristics of Sound - Intensity
1.3.5 Doppler Effect
Summary
Unit 2.1 Multiple Choice Extended Questions - Waves
Unit 2.1 Multiple Choice Extended Answers-Waves
Unit 1.3 Multiple Choice Questions - Sound
Unit 1.3 Multiple Choice Answers - Sound
 

Unit 1.3 Sound Waves

Characteristics of Sound

1.3.1 Speed of Sound

Recall:Sound waves travel at different speeds in different media - generally fastest in solids followed by liquids and tend to be slowest in gases.

We will now investigate the speed of sound in air.

General Equation

The speed of sound in a gas reduces to v = √(B/ρ) where B is the bulk modulus and the density...

Solids
v (ms-1)
Liquids
v (ms-1)
Gases
v (ms-1)
Rubber
1600
Water
1493
Air (20°C)
343
Aluminum
6420
Glycerol
1904
Air (0°C)
331
Steel
≈ 5000
Seawater
1533
Hydrogen (0°C)
1286
Wood
≈ 4500
Methyl alcohol
1143
Oxygen (0°C)
317
Glass
≈ 5000
Mercury
1450
Helium (0°C)
1005

Effect of Temperature

Sound traveling through the air move faster as temperature increases so v = (331 + 0.60T) ms-1, where T is in °C.

Questions:

1. Some older auto-focus cameras use sound waves for calculating the distance of the object. If the camera is calibrated for 0°C, how much time delay is there in an object at a distance of 30m away from the camera when used in at an ambient temperature of 30°C?

Answer = .....

 

2. P-waves (longitudinal seismic waves) in an earthquake travel about 7.0 X 103 ms-1 in the asthenosphere (mantle). If the average density of rock in the asthenosphere is 2.4 X 103 kgm-3, what is the bulk modulus of the Earth's crust? (Consider the Earth's asthenosphere to be a very viscous fluid).

Answer = .....

 

Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.