如果有人在擁擠的地方“排氣”，好像周圍的人都很快能聞到臭味。這種氣體比空氣傳播得更快嗎？它的速度是多少呢？

While anecdotal evidence circulating on the Internet states that farts travel an average of 10 feet（3 meters）per second， or nearly 7 miles per hour， a scientific determination of fart speed is more difficult to pinpoint. If we were to calculate the velocity of a fart， the kinetic theory of gases would offer useful guidelines. All gases — including those that escape the body during a fart — have properties that include temperature and pressure related to molecular motion. When gases are at the same temperature and volume， they will exert the same pressure against their containers. And， the greater the temperature of the gas， the more kinetic energy it will have， because heated atoms move faster than cooled atoms.

Measuring fart speed is problematic because of many variables. The composition of the gas itself， which can vary by food and by person， means the calculation would change for each fart. However， it is theoretically possible to find an average fart speed based on the typical composition and volume of an average fart. According to Ohio State University， the typical fart volume is about 2 liters a day and the average person farts 10 to 20 times a day.

In the end， it may be easier to gauge the sound of a fart than the speed. If youd really like to impress your friends， compare your fart to the speed of sound， an impressive 760 miles（340 meters）per second. Unless theyre really into chemistry， theyll never know whether your fart was particularly speedy — or not.