PHYS 1A Lecture Notes - Lecture 1: Dimensional Analysis, Significant Figures, Metric Prefix
Document Summary
Lecture 1 - september 23, 2016 - week 0. Useful way of writing large and small numbers. 178, 000, 000, 000 miles = 1. 78 1011 miles. 0. 00000003 meters = 3 10-8 meters. Units are standards for measuring physical quantities. In phys 1a, all units will be combinations of length, mass, time and will have special names. Base units are meters (m), kilograms (kg), seconds (s) Peta is 1015: working with units. Can only add and subtract similar units. M + m is okay, but not m + cm. During multiplying and dividing, units will come along. Conversion factors are ratios of 1: significant figures. Keep smallest number of decimal places for adding and subtracting. Keep smallest number of significant figures for multiply and dividing. Infinite significant figures for definitions and whole numbers. Use scientific notation to keep significant figures clear: dimensional analysis. Units can help check and derive relationships. Result will usually be valid to some constant: sanity-checking equations.
