AGENDA

• Use the SI system of measurements

• Convert from one system of units to another system of units • Determine the number of significant figures in the analysis and measurements

• Understand the meaning of vectors

• Graphically add and subtract vectors

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CLASSICAL MECHANICS

• Isaac Newton’s Principia (1687)

• Applications

Astronomy, chemistry, geology, engineering

• How and why things work

• Classical

Not too fast ( v > atom)

STANDARD UNITS

• Physics is based on measurement

• Three fundamental quantities

Length

Mass

Time

• mks system of units (1960)

• cgs system of units

• Derived units

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SYSTEM OF UNITS

• SI (Systėm International) Units

mks

L = meters;

M = kilogram; T = seconds

• British Units

L = inches; M = slugs (pounds) lb; T = seconds

• Gaussian Units

cgs

L = centimeter; M = gram; T = seconds

Know How to Convert!

PREFIXES FOR POWER OF TEN

Power

Prefix

Abbreviation

10-18

atto

a

10-15

femto

f

10-12

pico

p

10-9

nano

n

10-6

micro

10-3

milli

m

10-2

centi

c

103

kilo

k

106

mega

M

109

giga

G

1012

tera

T

1015

peta

P

1018

exa

E

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MEASUREMENTS ARE IMPORTANT

• Spacecraft launched (12-111998) to study Mars

• Burned up in Mars atmosphere

(09-23-1999)

NASA (09-30-1999) issues a statement, stating that a likely cause of mission failure is the use of incompatible scientific units among engineering teams

(English units versus metric units). • Cost of the mission was about

650 million dollars https://resources.tstc.edu/j/BEST/public/26/Team_engineering_case_study.pdf SIGNIFICANT FIGURES

• Significant figure refers to the number of digits that actually have meaning as a result of measurement

All non-zero digits are significant

Leftmost non-zero digit is the most significant digit

All digits in scientific notation are significant

Exact numbers have zero uncertainty

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SIGNIFICANT FIGURES -