# PHY 125

Published on: Mon Jan 25 2010

Thoughts on the first day of class It rained a lot today. I’m soaking wet. PHY 125: This is a class about classical Mechanics: describing mechanical objects. (How its forces work). Objects are generally described in relation to an origin. To describe an object, you want to put its mass into a location and a time. There are three main standard units used in the Si (System International) to describe inertia, location and time. Mass = Inertia/Weight (In Gravity field) = gram Location = x,y,z coordinates in relation to an origin = meter Time = second (Time is unique, it flows forward. You can’t go backwards (yet?)) These three basic standard units can be combined in various methods to describe mechanics. Since Location and Mass are based off the unit of ten, there are many powers of ten which are used to describe smaller and larger units. They are: Larger 10 power 3 = kilometer/kilogram = 1*1000 10 power 1 = meter/gram =1/1 Smaller 10 power -2 = centimeter/centigram = 1/100 = One hundredth of a meter 10 power -3 = millimeter/milligram = 1/1,000 = One thousandth of a meter 10 power -6 = micron/microgram? = 1/1,000,000 = One millionth of a meter 10 power -9 = nanometer/nanogram? = 1/1,000,000,000 = One billion of a meter 10 power -12 = picometer = 1/1,000,000,000,000 = One trillionth of a meter 10 power -15 = femtometer 1/1,000,000,000,000,000 = One quadrillionth of a meter