PY 131 Chapter 20: Sound

What is stress in a body?

Stress is the average force per unit area that an element of a body exerts on an adjacent element across an imaginary surface that separates them.

What is the normal stress in a fluid?

In a fluid, the normal stress is the pressure.

What is sound in a body?

Sound is a wave of stress in a body that acts as the medium.

What is the difference between the form of sound waves in fluids and solids?

In fluids, sound only has a longitudinal form, while in solids, it can be both longitudinal and transverse.

What is the range of human hearing?

The range of human hearing is about 20 Hz to 20,000 Hz.

What is the difference between subsonic and ultrasonic sound waves?

Sound waves with frequencies below 20 Hz are called subsonic, while sound waves with frequencies above 20,000 Hz are called ultrasonic.

What is the relationship between the speed of sound and the density of a gas?

At a given pressure and temperature, less dense gases have higher sound speeds.

What happens to the speed, frequency, and wavelength of a sound wave when it passes from air to water?

The speed of the wave increases, while the frequency stays the same, and the wavelength increases.

What is the beat frequency?

The frequency difference between two interfering waves of different frequencies is called the beat frequency.

What is the fundamental wavelength of a taut string?

The fundamental wavelength of a taut string is twice the length of the string.

What is the relationship between the tension and speed of waves on a string?

The speed of waves on a string depends on the tension in the string.

What is the frequency of the fundamental harmonic on a taut string?

The frequency of the fundamental harmonic on a taut string is given by f1 = v/λ1, where v is the speed of waves on the string and λ1 is the fundamental wavelength.

What happens to the frequency of the harmonics when the tension in a string is changed?

The frequencies of the harmonics change when the tension in a string is changed.

What happens to the wavelengths of the standing waves on a string when the length of the string is changed?

The wavelengths of the standing waves on a string change when the length of the string is changed.

What is the relationship between the frequency of the harmonics on a taut string?

The frequency of the nth harmonic is given by fn = nf1.

What is the difference between the fundamental and overtones on a stringed instrument?

The fundamental is the lowest frequency standing wave on a string, while overtones have higher frequencies and are integer multiples of the fundamental.

What is the mechanism by which a musical instrument produces sound?

The vibrations of a musical instrument cause the nearby air to be displaced, creating changes in local air pressure that travel as sound waves to a detector, such as your ear.

What is the difference between the speed of waves on a musical instrument and the speed of sound in air?

The speed of waves on a musical instrument can be different from the speed of sound in air.

What is the difference between normal stress and shear stress?

Stress is divided into normal stress and shear stress. Normal stress is the average force per unit area perpendicular to a surface, while shear stress is the average force per unit area parallel to a surface.

What is the relationship between the frequency of adjacent musical notes?

The ratio of frequencies of adjacent notes is constant, ^12√2.