08-14-2003, 04:04 AM
Join Date: Feb 2003
...you think? It should be perfectly clear. Maybe you are having trouble with your metic units. A dyne is the unit of force in the cgs (centimeter-gram-second) metric system. A mass of one gram, at rest at sea level, experiences a gravitation field of 980 cm/sec squared. The force on the one gram mass is therefore 980 gram-cm/sec squared. A gram-cm/second squared is a dyne, so the weight of one gram is 980 dynes. A cubic centimeter of water has a mass of 1 gram, and a weight of 980 dynes. If we had a column of water 1 cm on a side, that was 102 cm high, it would weigh 1,000,000 dynes, and the water pressure at the bottom of the water column would be 1,000,000 dynes/sq centimeter, or one bar. That is almost one atmosphere, which is 1.013 bar.
OBTW, a lot of the confusion revolves around the British engineering system's use of the pound as both a unit of force and a unit of mass. A mass of one pound weighs one pound. These two units are actually called pound-mass (lbm.) and pound-force (lbf.) To convert one lbm. to .lbf, multiply by 32.2 feet/sec. squared.
Metric doesn't do this, in the standard system, (SI) the unit of mass is the kilogram, and the unit of force is the Newton. One kilogram weighs 9.8 Newtons. One gram weighs 980 dynes. One pound weighs 1 pound. Clear now?