Physics 111 Honors Classical Mechanics

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Physics 111 Honors Classical Mechanics

• Prof. Haimin Wang
• haimin_at_flare.njit.edu
• http//solar.njit.edu/haimin

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My Research Solar Physics Instrumentation Magneti
c Fields and Solar Activity
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Week 1

• Chapter 1 Sections 16
• Measurement
• International System of Units (SI System)
• Conversion of Units
• Length
• Time
• Mass

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Measurements

• Use laws of physics to describe many different
  physical systems
• Small set of simple laws
• Common language is mathematics
• Test laws by experiments
• Select smallest set of standards and derive other
  standards
• International Bureau of Weights and Measures
  (Paris), National Bureau of Standards, etc.
• Système Internationale (SI), International System
  of Units, metric system, or mksA system

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SI Units
Length meter m
Mass kilogram kg
Time second s
Electric current ampere A
Thermodynamic temperature kelvin K
Luminous intensity candela cd
Amount of substance mole mol
Why should we care about SI units? Mars Climate
Orbiter http//mars.jpl.nasa.gov/msp98/orbiter
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Prefixes for SI Units
10x Prefix Symbol
x18 exa E
15 peta P
12 tera T
9 giga G GeV
6 mega M MeV
3 kilo k keV
2 hecto h
1 deca da
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Prefixes for SI Units
10x Prefix Symbol
x ?1 deci d
?2 centi c cm
?3 milli m mm
?6 micro µ µm
?9 nano n Nm
?12 pico p Pm
?15 femto f fm
?18 atto a
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Example of Length
Measurements Length (m)
Distance to 1st galaxies 2x1026
Distance to Nearest Star (Proxima Centauri) 4x1016
Distance to Pluto 6x1012
Radius of Earth 6x106
Height of Mt. Everest 9x103
Thickness of this page 1x10-4
Radius of hydrogen atom 5x10-11
Radius of a proton 1x10-15
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Time

• 1 second is the time taken by 9,192,631,770
  oscillations of the light emitted by cesium-133
  atom
• Speed of light c299,792,458 m/s

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Example of time
Measurements Time (second)
Age of Universe 5x1017
Length of a year 3x107
Length of a day 9x104
Lifetime of muon 2x10-6
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Mass

• Standard 1 a platinum-iridium cylinder in Paris
• Standard 2 Carbon-12 has 12 atomic mass units
  (u). 1u1.6605402x10-27 kg

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Example of mass
Objects Mass (kg)
Sun 2x1030
Moon 7x1022
Ocean Liner 7x107
Human Body 6x10
Speck of dust 7x10-10
Proton 2x10-27
Electron 9x10-31
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Units

• Language is mathematics
• Equations
• Diagrams/visualization
• Quantities have dimensions
• Results have units
• Consistency

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Precision

• Measurements
• Uncertainties
• Absolute
• Percent
• Calculation
• Result can not be better than data
• Use scientific notation to show significant
  figures
• Examples
• 3.14 0.5 3.6
• 123,400,000 1.234 x 108
• 0.003 3 x 10-3

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What is the radius r of the Earth? (h 1.70 m
and t 11.1 s )