SOUND |
|---|
| by Ted Peterson |
|---|
|
|---|
| People see in the paper or on TV, talk about the speed of sound or that ships can check the depth of the ocean by sound. |
|---|
|
|---|
| Sound travels in air at about 1,100 feet per second. The precise speed is 331.4 meters a second. This is at the temperature of 32 degrees F. or 0 degrees C. |
|---|
|
|---|
| If you would like to figure the speed at a different temperature you can use the following formula. This is in air. V=331.4 + 0.6Tc m/s. (c is temperature in Celsius). You need to change your fehrenheit temperature to celsius. At this point you need to change the feet/second to miles/hour to come up with distance covered in one hour. |
|---|
|
|---|
| This makes 1,193,040 meters / hour at 0 degree C. That is 745.65 miles per hour. That is the speed that you see in the newspapers and on TV. |
|---|
|
|---|
| By going to the scale above you see that the speed goes up the higher the temperature, and goes down as the temperature goes down. At 20 degree C. the speed is up to 344 meters / per second or 769,671 miles per hour. By going higher up in the sky, the speed can change a little but you do not need to figure it in. |
|---|
|
|---|
| When airplanes are flying, the speed of sound, it is called by the unit in Mach. Mach 1 is the speed of sound. When a jet is traveling below the speed of sound you will hear the airplane before the aircraft is there. When the plane is traveling faster then the speed of sound it will out run the sound and cause a shock wave to be generated that can hit the earth and cause damage. That is the reason that planes flying faster then the speed of sound have to fly over oceans or extremely high up. Some of the Air Force planes will travel up to 2,000 miles per hour. 747, etc. planes will travel under 650 miles a hour. |
|---|
|
|---|
| Sound travels at different speeds faster or slower when traveling through other items. Metal at 16,000 feet per sec. Glass at 14,900 feet per second. Sea water at 5,023.25 feet per second. |
|---|
|
|---|
| Ships use the speed of 5,023 to tell how deep the sea water is or how deep a submarine is by sending down a tone and recording the time it takes the sound to come back by its echo. They can also listen for the sound of the motor between 2 different ships. Then they can tell where that sub is. |
|---|
|
|---|
| People can hear from 20 to 20,000 hertz's. As the person get older the top limit will go down. Most people will have a higher level on their lower limit then 100 cycles but some people can also hear the sound of their power lines of 60 cycles. Dogs will have a top limit of up to 50,000 and cats will have a top limit of 65,000. Bats will have the top of almost thing around people . Their top will be over 120,000 cycles. |
|---|
|
|---|
| The volume is listed in decibels. Most people can hear 20 db and up. Speech is 60 decibels. You will hear pain if sound is higher then 140 decibels, some people lower limit. Rock music can be over 120 decibels. |
|---|
|
|---|
| When you hear echos you are hearing reflections from some thing. Most of the time when sound hit any thing the item will absorb the sound. Some things will either bounce back the sound or will change the sound by adding to the frequency and you will get a echo back that sounds different. |
|---|
|
|---|
| In outer space there is no sound because it has no air, etc to travel in. |
|---|
|
|---|
|
|---|
| If you would like to go back to the information index: click here. |
|---|
| If you care to go to the opening menu: click here. |
|---|
| If you care to go to the articles menu; click here. |
|---|
| |
|---|
Any Comments, Questions, or Inquiries:  E-Mail_w7wwg@jps.net
|
|---|