Pressure

**Pressure (Work in-progress)**
By Ethan Bennis and Nandish Pathak

Gas particles are in constant random motion, and thus they are continuously colliding with each other and the surfaces around them, exerting force. Pressure is the measurement of the force which a gas exerts on a certain area. It is an extremely important variable property of gas, and is needed in most gas-related calculations.

There are several tools that can be used for measuring pressure but the one most commonly used tool is probably the barometer. The barometer has been around for a while; it was invented in 1643 by Evangelista Torricelli (A student of Galileo), but the concept for the device is still the same today. It consists of a glass tube that is at least 760mm long that is sealed at one end and filled with mercury. The mercury is exposed to the natural air pressure around it, so the pressure can be measured by the height of the mercury in the tube. Standard atmospheric pressure is the pressure that can support a column of mercury 760mm high. It equals 1.01325x10^5 pascals in SI units. Other units of pressure include atmosphere(atm), torr, and mm Hg. the conversion between the units are:

code 1atm = 760mmHg = 760torr = 1.01325x10^5 Pa = 101.325 kPa = 14.7 psi code

How to find pressure
Pressure is directly related to the force of an object, or the push that tends to move something else in a given direction, and inversely related to the area of the force. The force of an object is the product of its mass and acceleration. combined equation:
 * Pressure = Force / Area**
 * Force = Mass x Acceleration**
 * P = ma / A**

Sources: http://www.infoplease.com/ce6/sci/A0806263.html Chemistry: The Central Science (9th Edition) by Brown, LeMay, and Bursten. Picture: http://umpgal.gsfc.nasa.gov/www_root/homepage/uars-science/BrochurePage1.html