Upload
collin-ball
View
226
Download
10
Embed Size (px)
Citation preview
Data AnalysisChapter 2
What’s wrong with this sign?
Temperature
30°C 30°F
Système Internationale d’ Unités
SI unit
Prefixes used with SI units
English vs. Metric Units
Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167Right Image: http://share.lancealan.com/N800%20ruler.jpg
Which is longer?
A. 1 mile or 1 kilometer
B. 1 yard or 1 meter
C. 1 inch or 1 centimeter
1.6 kilometers
1 mile
1 yard = 0.9444 meters
1 inch = 2.54 centimeters
Metric Units of Length
The basic unit of length in the metric system in the meter and is represented by a lowercase m.
Metric Units
1 Kilometer (km) = 1000 meters
1 Meter = 100 Centimeters (cm)
1 Meter = 1000 Millimeters (mm)
Which is larger?
A. 1 meter or 105 centimeters
B. 4 kilometers or 4400 meters
C. 12 centimeters or 102 millimeters
D. 1200 millimeters or 1 meter
Measuring Length
How many millimeters are in 1 centimeter?
What is the length of the line in centimeters? _______cm
What is the length of the line in millimeters? _______mm
1 centimeter = 10 millimeters
What is the length of the line to the nearest centimeter? ________cm
English vs. Metric Units
Which is larger?
1. 1 Pound or 100 Grams
2. 1 Kilogram or 1 Pound
3. 1 Ounce or 1000 Milligrams
1 pound = 453.6 grams
1 kilogram = 2.2 pounds
1 ounce of gold = 28,349.5 milligrams
Metric Units of mass
Mass refers to the amount of matter in an object.
The base unit of mass in the metric system in the kilogram and is represented by kg.
Metric Units
1 Kilogram (km) = 1000 Grams (g)
1 Gram (g) = 1000 Milligrams (mg)
Which is larger?
A. 1 kilogram or 1500 grams
B. 1200 milligrams or 1 gram
C. 12 milligrams or 12 kilograms
D. 4 kilograms or 4500 grams
Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram
English vs. Metric Units
Which is larger?
A. 1 liter or 1 gallon
B. 1 liter or 1 quart
C. 1 milliliter or 1 fluid ounce
1 gallon = 3.79 liters
It would take approximately 3 ¾ 1-liter bottles to equal a gallon.
1 fl oz = 29.573 ml
1 12-oz can of soda would equal
approximately 355 ml.
1 quart = 0.946 liters
Metric Units
Volume is the amount of space an object takes up.
The base unit of volume in the metric system in the liter and is represented by L or l.
Metric Units
1 liter (L) = 1000 milliliters (mL)
1 milliliter (mL) = 1 cm3 (or cc) = 1 gram*
Which is larger?
A. 1 liter or 1500 milliliters
B. 200 milliliters or 1.2 liters
C. 12 cm3 or 1.2 milliliters*
Measuring Volume
We will be using graduated cylinders to find the volume of liquids and other objects.
Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water.
What is the volume of water in the cylinder? _____mL
What causes the meniscus?
A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.
Measuring Liquid Volume
Imag
es c
reat
ed a
t ht
tp:/
/ww
w.s
tand
ards
.dfe
s.go
v.uk
/prim
aryf
ram
ewor
k/do
wnl
oads
/SW
F/m
easu
ring_
cylin
der.
swfWhat is the volume of water in each cylinder?
Pay attention to the scales for each cylinder.
Measuring Solid Volume
10 cm
9 cm
8 cm
We can measure the volume of regular object using the formula length x width x height.
_____ X _____ X _____ = _____
http
://re
sour
ces.
edb.
gov.
hk/~
s1sc
i/R_S
1Sci
ence
/sp/
en/s
ylla
bus/
unit1
4/ne
w/te
stin
gmai
n1.h
tm
We can measure the volume of irregular object using water displacement.
Amount of H2O with object = ______
About of H2O without object = ______
Difference = Volume = ______
Temperature Scales
How hot? How cold? direction of Heat Transfer
Celsius – 0 0C Freezing Point of Water
100 0C Boiling Point of Water
Kelvin = C° + 273 No degree signs are used O Kelvin = -273.150 C
▪ coldest possible temperature
What is the metric unit for…?
Length – size meter (m)
Mass – amount of matter Kilogram (kg) or gram (g)
Volume – space something takes up Liter (l) or centimeters cubed (cm3)
Temperature – amount of heat Kelvin (K) = celsius + 273
Density
Measure of how much matter is squeezed into a given space
density = mass volume
Which one is more dense?
A block of wood and a block of steel have the same volume
What do you think?
What happens to the density of an object if it is cut into pieces?
Which has the greater density, a single uranium atom or Earth?
Scientific Notation
coefficient x 10 raised to a power
Single gram of hydrogen 602,000,000,000,000,000,000,000
molecules = 6.02 x 1023 molecules
Mass of an atom of gold 0.000000000000000000000327 grams
= 3.27 x 10-22 grams
Practice
36,000 3.6 x 104
503,000,000 5.03 x 108
0.00076 7.6 x 10-4
Significant Figures
The valid digits of a number In measurement: includes all of the
digits that are known, plus a last digit that is estimated
Significant Figures
Significant: nonzero digits final zeros after the decimal points zeros between two other significant
digits
Not significant zeros used solely for spacing the decimal
point are not significant.
Examples
each have only two sig figs 0.0071 meter 0.42 meter 0.000099 meter
7.1 x 10-3 meter4.2 x 10-1 meter9.9 x 10-5 meter
Significant Figures
Value
5.60
5.6
0.012
0.0012003
0.0120
0.0012
# of significant figures
3
2
2
5
3
2
Rounding
If the digit immediately to the right of the last significant digit is less than 5, it is dropped 5 or greater - last significant digit
increased by 1 41.58 square meters 41.6 square
meters
Practice
Round 65.145 meters to 4 sig figs 65.15m
Round 100.1°C to 1 sig fig 100°C
Round 154 cm to 2 sig figs 150
Round 0.000718 kilograms to 2 sig figs 0.00072
Measurements with an Unlimited Number of Significant Digits
Counting Example: 23 people in the classroom
▪ (Not 22.9 or 23.1) 23.00000000……………….
Exactly defined quantities Example: 60 minutes = 1 hour
▪ 60.00000000……………………..
Calculation Rules
calculated answer cannot be too precise not more precise than the least precise
measurement
Multiplication and Division same number of sig figs as the
measurement with the least number of sig figs
Addition and Subtraction same number of decimal places as the
measurement with the least number of decimal places
Accuracy and Precision
Accuracy How close a
measurement comes to the actual value of what is being measured
Precision How close a series
of measurements are to one another
Error
Difference between accepted value and experimental value
error = experimental value – accepted value
% error = x 100% error
accepted value
Error
% error = x 100%
99.1°C – 100.0°C x 100% 100.0°C
0.9°C x 100% 100.0°C
0.9%
error
accepted value
=
=
=