The pressure is on

Today in class, we learned about pressure and saw a few demos. We saw Mr. Lieberman lay down on a bed of nails, and then a few of us got to try as well. The reason people didn't get stabbed to death by the nails is that pressure equals force divided by area (P=F/A). He explained that no matter how big or small an object is, the force remains the same. The dependent part is the area. The bigger the object on the nail bed, the less pressure is on them due to the increase in area.
http://www.flickr.com/photos/hc1011/5241587429/

We also learned the different units for measuring pressure, and the conversions between them. They are: pounds per square inch (psi), atmosphere (atm), Torr, or millimeters of mercury (mmHg), and pascal (Pa). The conversions are: 14.7 psi=1 atm=760 mmHg=100 kPa. We also went over how barometers and manometers work, with the atmosphere pushing down to show the pressure.

We went over Dalton's law too, which states that the sum of partial pressures of gases equals the total pressure of the gases when combined. So, if gas 1 is 1 atm and gas 2 is 2 atm, when they are combined the pressure is 3 atm. Boyle's law deals with pressure and volume, stating that the product of the pressure and volume for a gas equals a constant, k (PV=k). So no matter what differences in pressure or volume occur, P1V1=P2V2.

We also got to see Brandon and Zoe get stuffed in a trash bag and have the air sucked out to demonstrate the actual air pressure here on earth, as well as see an inflated balloon expand when the air is sucked out. Happy late arrival tomorrow, and the next scribe is Peter W.
http://www.flickr.com/photos/hc1011/5241588237/
http://www.flickr.com/photos/hc1011/5241588451/