1. DATA

2. SCIENCE is… the search for relationships that explain
and predict the behavior of the universe.

3. PHYSICS is… the science concerned with relationships between matter,
energy, and its
transformations.

4. There is no such thing as absolute certainty of a scientific claim.
The validity of a scientific conclusion is always limited by:
the experiment
design, equipment, etc...
the experimenter
human error, interpretation, etc...
our limited knowledge
ignorance, future discoveries, etc...

5. an experimentally confirmed explanation
Scientific Law
a statement describing a natural event
Scientific Theory
an experimentally confirmed explanation
for a natural event
Scientific Hypothesis
an educated guess (experimentally untested)

6. perception of “Communist” system natural resistance to change
developed in France in 1795
a.k.a. “SI” - International System of Units
The U.S. was (and still is) reluctant to “go metric.”
very costly to change
perception of “Communist” system
natural resistance to change
American pride

7. The SI unit of: length is the meter, m time is the second, s
mass is the kilogram, kg.
electric charge is the Coulomb, C
temperature is the degree Kelvin, K
an amount of a substance is the mole, mol
luminous intensity is the candle, cd

8. “Derived units” are combinations of these “fundamental units”
The second is defined in terms of
atomic vibrations of Cesium-133 atoms.
The meter is defined in terms of the speed of light.
The kilogram is still defined by
an official physical standard.
“Derived units” are combinations
of these “fundamental units”
Examples include speed in m/s, area in m2,
force in kg.m/s2, acceleration in m/s2,
volume in m3, energy in kg.m2/s2

9. exa E
peta P
tera T
giga G
106 mega M
kilo k
102 hecto h
deka da
atto a
femto f
pico p
nano n
micro m
milli m
centi c
deci d

10. Explore the metric system at link1, link2, and link3.
See definitions of metric units here.
Click here to do conversions.

11. Precision Accuracy % error = x 100% accepted - observed accepted
All measurements have some degree of uncertainty.
Precision
single measurement - exactness, definiteness
group of measurements - agreement, closeness together
Accuracy
closeness to the accepted value
accepted - observed
accepted
% error =
x 100%

12. Example of the differences between precision and accuracy for a set of measurements:
Four student lab groups performed data collection activities in order to determine the resistance of some unknown resistor (you will do this later in the course). Data from 5 trials are displayed below.
Suppose the accepted value for the resistance is 500 Ω.
Then we would classify each groups’ trials as:
Group 1: neither precise nor accurate
Group 2: precise, but not accurate
Group 3: accurate, but not precise
Group 4: both precise and accurate
Group
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
avg 1 34
612 78
126
413
132.6 2
127
128
125
126.4 3 20
500 62
980
938 4
502
501
503
498
499
500.6

13. 1. All non-zero digits are significant.
2. Zeros between other significant
digits are significant.
3. Leading zeros are not significant.
4. Final zeros before the decimal
are not significant.

14. Addition and Subtraction (link)
Operations with Significant Digits
Addition and Subtraction (link)
round the sum or difference
to the least precise decimal place
Multiplication and Division (link)
round so that the product or quotient
has a total number of significant digits
equal to the total number of significant digits
of the least precise quantity

15. Learn more about significant digits here and here.
Check your understanding here and here.
The “bottom line” is that the precision to which a
measured or calculated amount is written provides
valuable information as to the precision (certainty)
of that value and the device used to measure it.