Transcript Chapter 2 Notes - Tri-City

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This should be review
The metric system – used by everyone but the
United States.
› Also called SI or Systeme de Internationle d’Unites or
international systems of units and measurements
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Length – meter
Mass – gram
Time - second
Temperature – kelvin
Amount of substance – mole
Electric current – ampere (amp)
Luminous intensity - candela
Kilo – 1000 base units
 Centi - .01 base units or 1/100th of a base
unit
 Milli - .001 or 1/1000th of a base unit
 micro - .000001 or 1/1,000,000 of a base
unit
 Nano - .000000001 or 1/1,000,000,000 of a
base unit
 Full list is on page 18 of textbook
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Shorthand way to express a large number
with lots of 0’s
1,000 is 103
1,000,000 is 106
1/1,000 is 10-3
Can also be used to represent numbers that
are not 10 base units.
3,000 is 3 x 103
3,000,000 is 3 x 106
.003 is 3 x 10-3
Does everyone remember the
“stairstep”?
 1000g x 1kg/1000g = 1kg
 500cm x 1m/100cm = 5m
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Do Practice Problems 1-5 on pages 20-21
in the textbook ( 5-6 minutes) GO!!
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To Add or subtract: Convert to same
exponential value then perform addition
or subtraction
› Ex: 4 x 108 + 3 x 108 = 7 x 108
› 4.02 x 106 + 1.89 x 102
 40,200 x 102 + 1.89 x 102
 (40,200 + 1.89) = 40,201.89 x 102
 1.89 is a small value so 4.02 x 106 once we move
decimal points.
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To multiple and divide: no need to convert
just multiple or divide M number then
add/subtract exponents to solve
Ex: (4 x 103) x (5 x 1011)
(4 x 5)= 20
103 + 1011 = 1014
So 20 x 1014 or 2.0 x 1015
Do Practice Problems p. 22-23 (8abcd, 9ab,
10ab)
Pg. 23
 Questions 1-4
 Use complete thoughts and
grammatically correct sentences.
 Be worth around 20pts
 Due tomorrow.
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Comparing Results
 Must have overlap when the standard
deviation is factored in.
 19.0 +/- 0.2cm and 18.8 +/- 0.3cm
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› Overlap covers 18.8cm to 19.1cm
› These two measurements agree.
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Precision – describes
the exactness of a
measurement.
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Accuracy – describes
how well the results
agree with the
standard value.
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Target Example:
Be sure you are using the correct
instrument to measure with.
 Use that instrument correctly
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› Meter stick should be laid flat so that your
eye is directly above the stick.
› Reading at an angle will cause inaccuracies
in measurement due to parallax – the
apparent shift in the position of an object
when it is viewed at different angles.
› Thumb Parallax
Significant digits – the valid digits in a
measurement.
 Usually limited by the instrument you use.
 Ex: A meter stick or ruler may only have
marks showing 0.1cm so measurements
can have only two digits past your
decimal. The known and then the final
estimated digit.
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1.
All non-zero digits are significant.
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All final zeroes after the decimal are
significant
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Ex: 1.20, 1.000
Zeroes between other significant digits
are also significant.
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4.
Ex: 1.45, 55, 453.9
Ex: 405, 10,101
Zeroes used as a placeholder are not
significant
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Ex: 0.001, 0.0005
Your answer can NEVER be more precise
than your least precise measurement.
 When adding and subtracting you simply
round your answer to the value with the
lowest number of significant digits.
 Ex: 24.355 + 12.45 + 10.9 = 47.71 but using
the significant digits the answer we need
is 47.7 because 10.9 only has one
significant digit after the decimal and
47.71 rounds down to 47.7
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When multiplying or dividing: do the math
then round again to the number with the
lowest number of significant digits.
 Ex: 3.22 x 2.1 = 6.762, should round to 6.8
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Using a Calculator: Can often display many
meaningless digits. Be sure to pay attention
to significant digits. I don’t want an answer
given to 12 decimal places, just because
you are anal retentive and tend to be too
precise. I will wear out a red pen on that
answer.
Pg. 29
 Questions 2.1-2.4
 Due tomorrow
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Objectives:
› Be able to read and interpret graphs
showing linear and nonlinear relationships
between variables
› Use graph trends to predict outcomes
› Recognize quadratic and inverse
relationships
Graphs are the easiest way to analyze
data.
 When creating a graph, one must be
sure to plot the pertinent information:
independent vs dependent variables.
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Look at Table 2.3 on pg. 30 of the
textbook: What type of experiment is
shown in that table?
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Strategy for making a Line graph
› ID the variables: independent is plotted on
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horizontal (X-axis) and dependent on the
vertical (Y-axis).
Establish a range for each measurement and
establish your origin (0,0)
Create axis labels that give an even spacing of
numbers within your range.
Plot the data to the best of your ability.
Draw a “best fit” line or a curve through as many
data points as possible
Decide on a title for graph that states what is
shown on it.
All you need is SLOPE
 Linear relationships are plotted using
slope intercept formula: y=mx+b
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Y = y coordinate
M = slope
B = y intercept
X = x coordinate
Slope is calculated using Rise/Run or
change in Y divided by change in X
You need any 3 points and you can
solve for the remaining.
 To solve for B, you must assume X = 0 and
you will need slope as well.
 Example:
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› Two sets of data points (2,2) and (4, 6)
 Calculate slope, find the y-intercept, and
derive the full equation for the line.
 5 minutes……GO!!!
Slope = rise/ run or (6-2)/(4-2) = 4/2 or 2
 Y intercept = y = 2x + b
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› 2 = 2(2) + b
› 2=4+b
› b = -2
Equation for line: y = 2x – 2
 Also on line: (0, -2) (1, 0) (3, 4)……
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Represented by parabolic (parabola)
shaped line.
› One variable depends on the square of the
other variable.
Quadratic: y = ax2 + bx + c
 If you have a graphing calculator then
use it for these, its okay to be lazy.
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Some graphs can be represent an inverse
relationship.
› This means when one variable is doubled the
other variable goes down by a factor of 2 or ½
of original value.
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Y = a/x or
xy = a
› Both formulas show the proper relationship.
› Graph shape called a hyperbola
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Practice Problem 21: pg. 36 in text….Solve it
Pg. 36
 Questions 1-4
 Due tomorrow.
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Pg. 37-39
 1-17 odds, 18-29 odds
 Due tomorrow.
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