In Feet Per Second (FPS) how fast does a bullet have to go in order to break the sound barrier at sea level?

Answer 1

Speed of sound at sea level and 15C (59 F, i.e standard atmosphere) is 1116.45 feet per second.

Note that the speed of sound is highly dependent on the temperature.

Answer 2

1,120 feet per second, or 344 meters per second, or about 770 miles per hour.

http://en.wikipedia.org/wiki/Speed_of_sound

Also, the two answers below mine are absolutely correct -- the temperature of the air has a direct effect on the speed of sound through the air, so all three of these answers are correct. They are just based on different assumptions of the air temperature, since differenct sciences or engineering disciplines use different conditions as their "standard" baseline. I was using 21 degrees C (approximate room temprature) while they were using 15 degrees C and 0 degrees C as they noted. My bad for not stating my assumptions... ;)

As the wikipedia article states, an approximate speed of sound "c" in dry air, in meters per second, at temperatures near 0 °C, can be calculated using:

c = 331.5 + (0.6 * v)

where v is the temperature in degrees Celsius(°C).

So plugging in various temperatures, the results we come up with are as follows (using the conversion rate of 1 meter per second = 3.28084 feet per second):

1137 fps @ 25° C
1127 fps @ 20° C
1117 fps @ 15° C
1107 fps @ 10° C
1097 fps @ 5° C
1087 fps @ 0° C

Answer 3

From my trusty Glover's Pocket Reference,

In dry air, 0 degrees Celsius 1087.4 ft/sec = 741.4 mph

Answer 4

Isn't it somewhere around 700MPH? or about 58,333.333 FPS.