4.11

Sound is made when a source of energy forces the matter to _________.

• shake

• vibrate

• move

• stay still

Answer explanation

sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain.

Tags

NGSS.MS-PS4-1

A back-and-forth motion causing particles to move close together generates a _______.

• rarefaction

• surface wave

• transverse wave

• compression

Answer explanation

Compression is a region in a longitudinal wave where the particles are closest together.

A rarefaction is a region in a longitudinal wave where the particles are furthest apart.

Tags

NGSS.MS-PS4-1

Sound waves cannot travel through which of these ____.

• paper

• milk

• outer space

• hydrogen

Answer explanation

Sound needs a medium to travel through, it cannot travel through a vacuum.

Outer space is a vacuum

In which of these types of media will sound travel faster?

• solid

• liquid

• gas

• vaccum

Answer explanation

Sounds travel faster and farther in solids.

Tags

NGSS.MS-PS4-1

NGSS.MS-PS4-2

Loudness of waves is measured in ______________.

• hertz

• decibels

• watts

• meters/second

Answer explanation

We measure sound intensity (also referred to as sound power or sound pressure) in units called decibels. Decibels (dB) are named in honor of Alexander Graham Bell, the inventor of both the telephone and the audiometer. An audiometer is a device that measures how well a person can hear certain sounds.

Tags

NGSS.MS-PS4-1

The ____________ of a wave increases with increased energy.

• wave length

• amplitude

Answer explanation

Amplitude is the relative strength of sound waves (transmitted vibrations), which we perceive as loudness or volume. Amplitude is measured in decibels (dB), which refer to the sound pressure level or intensity.

Tags

NGSS.MS-PS4-1

The maximum safe level for loudness is __________.

• 0 dB

• 60 dB

• 85 dB

• 130 dB

Answer explanation

You can listen to sounds at 70 dBA or lower for as long as you want. Sounds at 85 dBA can lead to hearing loss if you listen to them for more than 8 hours at a time. Sounds over 85 dBa can damage your hearing faster. The safe listening time is cut in half for every 3-dB rise in noise levels over 85 dBA.

Frequency of waves is measured in __________.

• hertz

• decibels

• watts

• meters/second

Answer explanation

The lower the frequency, the fewer the oscillations. High frequencies produce more oscillations. The units of frequency are called hertz (Hz). Humans with normal hearing can hear sounds between 20 Hz and 20,000 Hz.

Tags

NGSS.HS-PS4-1

High frequency sounds have a high ___________ .

• pitch

• volume

• amplitude

• medium

Answer explanation

Pitch can be taken as the measure of sound frequency expressed in terms of Hertz. Higher the frequency, higher the pitch.

Tags

NGSS.MS-PS4-1

Sound needs a medium to travel in.

• True

• False

Answer explanation

Of the three mediums (gas, liquid, and solid) sound waves travel the slowest through gases, faster through liquids, and fastest through solids. Temperature also affects the speed of sound. Gases: The speed of sound depends upon the properties of the medium it is passing through.

Sound will not travel in a vacuum, ie. outer space.

Tags

NGSS.MS-PS4-1

NGSS.MS-PS4-2