PHYS 1023 Lecture Notes - Lecture 2: Metric System, Atomic Number, Thought Experiment
24 Aug 2016
School
Department
Course
Professor
Monday, February 1, 2016
Physics & Human Affairs
Chapter 2: Atoms
-Measurements
•How far is it to Tulsa, OK?
-120; 1.5-2; 192; 630,000?
•Units matter
•United States uses inch, foot, mile, gallon, pounds
•Scientists and the rest of the world use the metric system
-Basic distance unit is the meter
•Other metric units: liter, gram
-Meter? — 39 inches
•Why does it matter?
-Mars Climate Orbiter
-9/23/1999
-Crash due to mixing British and metric units
-Metric Distances
•Basic unit is meter (m); about 39 inches long
•Other measures are based on powers of 10
•Metric system reuses prefixes with all basic units
-Powers of 10
•Scientific notion
•Using powers of 10 makes very large numbers easier to handle
-100,000,000 = 10^8
-1,000,000,000,000 = 10^12 (trillion)
•Solar system is 1.2x10^13 m across
!1
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Monday, February 1, 2016
-12,000,000,000,000 m
•It also helps with small numbers
-0.001 = 1/1000 = 10^-3
-0.0000001 = 10^-7
•Diameter of an atom is 1.1x10^-10
-0.00000000011 m
-Math with Powers of 10
•Multiplying: add the powers
-10^2x10^5 = 10^2+5 = 10^7
-10^3 x 10^-7 = 10^3+(-7) = 10^-4 = 0.0001
-(4.2x10^3)(4x10^-4) = (4.2x4)x(10^3x10^-4) = 16.8x10-1
•Dividing: subtract powers
-10^2/10^6 = 10^2-6 = 10^-4
-10^3/10^-4 = 10^3(-4) = 10^7
-(1.6x10^4)/(4x10^7) = (1.6/4)x(10^4/10^7) = 0.4x10^-3
-Sizes in the Universe
•10^27 m — known universe
•10^23 m — galaxy clusters
•10^21 m — Milky Way galaxy
•10^17 m — nearby stars
•10^13 m — solar system
•10^9 m — sun
•10^7 m — Earth
•10^3 m — tall mountain
•10^2 — tall building
•10^0 = 1 m — human
!2
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
120; 1. 5-2; 192; 630,000: units matter, united states uses inch, foot, mile, gallon, pounds, scientists and the rest of the world use the metric system. Basic distance unit is the meter: other metric units: liter, gram. Crash due to mixing british and metric units. Metric distances: basic unit is meter (m); about 39 inches long, other measures are based on powers of 10, metric system reuses pre xes with all basic units. Powers of 10: scienti c notion, using powers of 10 makes very large numbers easier to handle. 1,000,000,000,000 = 10^12 (trillion: solar system is 1. 2x10^13 m across. 12,000,000,000,000 m: it also helps with small numbers. 0. 0000001 = 10^-7: diameter of an atom is 1. 1x10^-10. Math with powers of 10: multiplying: add the powers. 10^3 x 10^-7 = 10^3+(-7) = 10^-4 = 0. 0001. (4. 2x10^3)(4x10^-4) = (4. 2x4)x(10^3x10^-4) = 16. 8x10-1: dividing: subtract powers.
