Unit 12 Concepts

The approximate range of human hearing is

20 Hz to 20,000 Hz.

The wavelength of the fundamental frequency of a vibrating string of length L is

2L

Consider an open pipe of length L. What are the wavelengths of the three lowest tones produced by this pipe?

2L, L, 2L/3

The speed of sound in air at normal temperatures is about ____ m/sec.

340

The lowest tone to resonate in an open pipe of length L is 200 Hz. Which one of the following frequencies will not resonate in the same pipe?

900Hz

_________ does not affect the pitch of the note played on a musical string?

Color of the string

a loud noise created by a pressure wave that follows an object moving faster than the speed of sound

Sonic boom

An open pipe of length L is resonating at its fundamental frequency.

The wavelength is 2L and there is a displacement node at the pipe's midpoint.

Large horns such as tubas produce sounds with long wavelengths while flutes produce sounds with short wavelengths because:

The wavelength of sound produced is directly proportional to the size of the instrument

Sound waves cannot travel in

a vacuum

When an air column vibrates in a pipe that is open at both ends,

all harmonics are present

The Doppler effect occurs with

all waves

The loudness of a musical sound is a measure of the sound wave's

amplitude

In a resonating pipe which is open at both ends, there

are displacement antinodes at each end.

At a concert the oboe is playing a long steady note as you walk away from the stage at an accelerating velocity toward the rest room. The pitch of the sound that you hear, is

constantly decreasing

Due to the Doppler effect, the pitch of the siren of a fire truck moving away from you:

decreases

_________ factor that does not affect the pitch of a note played on a musical pipe

diameter of the pipe

A Doppler effect occurs when a source of sound moves

either towards you or away from you

Pitch depends on the ____ of a sound wave.

frequency

A train moves down the track toward an observer. The sound from the train, as heard by the observer, is ____ the sound heard by a passenger on the train.

higher in pitch than

In a resonating pipe which is open at one end and closed at the other, there

is a displacement node at the closed end and a displacement antinode at the open end.

Sound waves are

longitudinal waves

As a source of continuous sound approaches a constant speed, you will NOT be aware of an apparent increasing of its

loudness, frequency, and wavelength

A light source that moves towards an observer at very high speeds (more than half the speed of light) will appear

more blue

A light source that moves away from an observer at very high speeds (more than half the speed of light) will appear

more red

When an air column vibrates in a pipe that is closed at one end,

only odd harmonics are present

The highness or lowness of a sound is perceived as

pitch

The Doppler effect is characteristic of

sound, light, and water waves

Sound travels faster in

steel

The term applied to objects that travel at speeds exceeding the normal speed of sound in air is:

supersonic

The speed of a sound wave in air depends on

the air temperature

If you are on a train, how will the pitch of the train's whistle sound to you as the train moves?

the pitch will not change

True or False? A sound source of high FREQUENCY emits a high PITCH?

true

The Doppler shift explains

why the siren on a police car changes its pitch as it races past us