6-7 Sound

Light and sound contain energy in the form of vibrations. You know that light travels through empty space.  Sound however, can only travel through things that have mass.  Sound waves are actually formed from something that is made out of matter.  You can hear sounds under water, in air, and even through solid doors.

Sound vibrations are in the form of waves.  These waves travel out in all directions.  They are composed of air vibrating back and forth in the direction of travel.  You can hear singing coming from another room because the sounds are coming from someone's vibrating vocal cords.  The vocal cords vibrate the air.  The air vibrates next to your ear and in turn vibrates your eardrum.  The vibrating eardrum vibrates organs inside the ear and stimulates nerves.  The nerves tell the brain that sounds are being heard.  Unless a sound causes air next to the eardrums to vibrate,  the sound will not be heard.

Sound waves have wavelengths just as light waves do.  Fast vibrations result in short wavelengths.  Slow vibrations result in long wavelengths.

Sound travels through air at about 1,000 feet per second.  This is over 700 miles per hour.

Directions: Answer the questions about sound.

Sound contains energy in the form of .

Which of the following statements is true?

Sound can only travel through things that have mass.

Sound can travel through empty space.

Sound waves are formed from things that are made of .

Sounds can only be heard if air next to the vibrates.

Fast sound wave vibrations cause wavelengths.

Slow sound wave vibrations cause wavelengths.

Sound travels through air over 700 per hour.