Welcome to Physical Science Ms. C. Burke
Feb 22, 2016
Welcome to Physical ScienceMs. C. Burke
Ch 1-Science skillsScience vs. Technology
• SCIENCE= system of knowledge & the methods you use to find knowledge
• TECHNOLOGY= the application of scientific knowledge to improve the quality of life
• Which came first-science or technology?
What is Physical Science?PHYSICS= study of matter &
energy & the interactions between the two through forces & motion
• CHEMISTRY= study of the composition (what matter is made up of), structure, properties (what matter is like & how it behaves), & reactions of matter
What is the SCIENTIFIC METHOD?
• an organized plan for gathering, organizing, & communicating information
Problem/QuestionObservation/Research
Formulate a HypothesisExperiment
Collect and Analyze ResultsConclusion
Communicate the Results
Steps of the Scientific Method1. Problem/Question: Develop a question or
problem that can be solved through experimentation.
Steps of the Scientific Method
2. Observation/Research: Make observations and research your topic of
interest.
Do you remember the next step?
Steps of the Scientific Method
3. Formulate a Hypothesis: Predict a possible answer
to the problem or question.Example: If soil
temperatures rise, then plant growth will increase.
Steps of the Scientific Method4. Experiment: Test your hypothesis. Develop and
follow a procedure.Include a detailed materials
list.The outcome must be
measurable (quantifiable).
Steps of the Scientific Method5. Collect and Analyze
Results: In words, tables, charts, graphs, and/or
photographs.
Steps of the Scientific Method6. Conclusion: Include a statement that accepts or
rejects the hypothesis.What did you learn? What are possible improvements
to the procedures?
Steps of the Scientific Method
7. Communicate the Results: Be prepared to
present the project to an audience.
Lab reports!
Think you can name all seven steps?
Problem/Question
Observation/Research
Formulate a Hypothesis
ExperimentCollect and Analyze Results
ConclusionCommunicate the Results
Let’s put our knowledge of the Scientific Method to a
realistic example that includes some of the terms you’ll be needing to use and
understand.
Problem/QuestionJohn watches his grandmother bake bread. He ask his
grandmother what makes the bread rise.
She explains that yeast releases a gas as it
feeds on sugar.
Problem/Question
John wonders if the amount of sugar
used in the recipe will affect the size of the bread loaf?
Caution!Be careful how you use effect
and affect.Effect is usually a noun and
affect, a verb.“ The effect of sugar amounts
on the rising of bread.”“How does sugar affect the
rising of bread?”
Observation/ResearchJohn researches the areas of baking and fermentation and
tries to come up with a way to test his
question.He keeps all of his information on this topic in a journal.
John talks with his teacher and she
gives him an Experimental
Design Diagram to help him set up his
investigation.
Do you know the difference between the independent and
dependent variables?
Independent Variable
The independent, or manipulated variable, is a factor that’s intentionally varied by the
experimenter.John is going to use 25g., 50g., 100g., 250g., 500g. of sugar in
his experiment.
Dependent Variable
The dependent, or responding variable, is the factor that may change as a result of
changes made in the independent variable.
In this case, it would be the size of the loaf of bread.
Formulate a HypothesisAfter talking with his
teacher and conducting further research, he comes
up with a hypothesis.
“If more sugar is added, then the bread will rise
higher.”
Hypothesis The hypothesis is an educated
guess about the relationship between the independent and
dependent variables.
ExperimentHis teacher helps him come up with a procedure and list
of needed materials.
She discusses with John how to
determine the control group.
Control Group In a scientific experiment, the
control is the group that serves as the standard of
comparison.The control group may be a “no
treatment" or an “experimenter selected”
group.
Control Group The control group is exposed to the same
conditions as the experimental group, except
for the variable being tested.
All experiments should have a control group.
Control Group Because his grandmother always used 50g. of sugar in her recipe, John is going to use that amount in his
control group.
ConstantsJohn’s teacher reminds him to keep all other
factors the same so that any observed
changes in the bread can be
attributed to the variation in the
amount of sugar.
Constants
The constants in an experiment are all the factors that the
experimenter attempts to keep
the same.
Can you think of some constants for this
experiment?
ConstantsThey might include:
Other ingredients to the bread recipe, oven used,
rise time, brand of ingredients, cooking time,
type of pan used, air temperature and humidity
where the bread was rising, oven temperature,
age of the yeast…
ExperimentJohn writes out his
procedure for his experiment along
with a materials list in his journal. He has
both of these checked by his
teacher where she checks for any
safety concerns.
TrialsTrials refer to replicate
groups that are exposed to the same
conditions in an experiment.
John is going to test each sugar variable 3 times.
Collect and Analyze Results
John comes up with a table he can use to record his data.John gets all his
materials together and carries out his
experiment.
Size of Baked Bread (LxWxH) cm3
Amt. of Sugar (g.)
1 2 3 AverageSize (cm3)
25 768 744 761 758
50 1296 1188 1296 1260
100 1188 1080 1080 1116
250 672 576 588 612
500 432 504 360 432
Size of Bread Loaf (cm3)Trials
Control group
Collect and Analyze Results
John examines his data and notices that his control
worked the best in this experiment, but
not significantly better than 100g. of
sugar.
ConclusionJohn rejects his hypothesis, but
decides to re-test using sugar
amounts between 50g.
and 100g.
Experiment
Once again, John gathers his
materials and carries out his experiment.
Here are the results.
Can you tell which group did the best?
Size of Baked Bread (LxWxH) cm3
Amt. of Sugar (g.)
1 2 3 AverageSize (cm3)
50 1296 1440 1296 1344
60 1404 1296 1440 1380
70 1638 1638 1560 1612
80 1404 1296 1296 1332
90 1080 1200 972 1084
Size of Bread Loaf (cm3)Trials
Control group
ConclusionJohn finds that 70g. of sugar produces the largest loaf.
His hypothesis is accepted.
Communicate the Results
John tells his grandmother
about his findings and prepares to present his project in
Science class.
STEPS in the experiment
–Manipulated variable (Independent)= causes a change in another
–Responding variable (Dependent)= the variable that changes in response to the manipulated variable
STEPS in the experiment
• Controlled Experiment= a standard for comparison, hold a variable constant (does
not change)
Analyze Data w/ Graphs
• Graph= a visual display of info–Pie Graphs= shows how some fixed quantities are broken down into parts *must equal 100%
–Bar Graphs= show info collected by counting
Analyze Data w/ Graphs–Line Graphs= shows changes occurring over time• Direct proportion= ratio of 2 variables is constant, both increase or decrease
• Inverse (Indirect) proportion= as one variable increases the
other decreases, vice versa
Graphs
00.5
11.5
22.5
33.5
44.5
0 1 2 3 4 5 6
Flow Rate (gallons per minute)
Tim
e (m
inut
es)
Mass vs. Volume of Water
0
5
10
15
0 2 4 6 8 10 12
Volume (mL)
Mas
s (g
)Average Annual Precipitation
050
100150200
Prec
ipita
tion
(cm
)
Physical Science Grades
A28%
B55%
C17%
SCIENTIFIC THEORY versus
SCIENTIFIC LAW • Theory=an Explanation
based on many observations supported by experimental results (explains why things work the way that they do)
SCIENTIFIC THEORY versus
SCIENTIFIC LAW• Law=“rule of nature”
Evidence summed up by related observations & experimental results to describe a pattern found in nature.
SCIENTIFIC NOTATION • composed of two parts that
make very large or very small #s easier to work w/.
• a number between one & ten & a power of ten
• Ex. 3.0 x 104 (the exponent 4 says the decimal is really 4 places to the right of 3)
SCIENTIFIC NOTATION
• 0.00086=8.6x10-4
• 300,000,000= 3.0x108
Scientific Notation• When multiplying: multiply the #’s
before the x sign and add the exponents
(3.0 x 108 m/s) x (5.0 x 102 s)=(3.0 x 5.0) (108 + 2) (m/s x s)= 15.0 x
1010 m = 1.5 x 1011
m• When dividing: divide the #’s before x
sign and subtract the exponents 1.5 x 1011 m = 1.5 x 1011-8 s
3.0 x 108 m/s 3.0 = 0.5 x 103 s = 5.0 x 102 s
SI units= International System of Units
• used worldwid
e by scientists, based
on multiples
of ten
Prefixes Symbol Multiple of ten
kilo k 1000
hecto h 100deka da 10
root unit g, m, L 1
deci d .1 or 1/10
centi c .01 or 1/100
milli m .001 or 1/1000
CONVERSIONS
• King Henry Died ___ Drinking Chocolate Milk
• Metric prefix indicates how many times a unit should be multiplied or divided by ten
• Convert 5mL to L• Move decimal 3 places to the left, so 5mL=0.005L
k h d mLg
d c m
KILO1000Units
HECTO100
UnitsDEKA
10Units
DECI0.1
UnitCENTI
0.01Unit
MILLI0.001Unit
MetersLitersGrams
Ladder Method
How do you use the “ladder” method? 1st – Determine your starting point.
2nd – Count the “jumps” to your ending point.
3rd – Move the decimal the same number of jumps in the same direction.
4 km = _________ m
12
3
How many jumps does it take?
Starting Point Ending Point
4.1
__.2
__.3
__. = 4000 m
Try these conversions using the ladder method.
1000 mg = _______ g 1 L = _______ mL 160 cm = _______ mm
14 km = _______ m 109 g = _______ kg 250 m = _______ km
Conversion Practice
Compare using <, >, or =.
56 cm 6 m 7 g 698 mg
1 1000 160014000 0.109 .250
< >
Write the correct abbreviation for each metric unit.
1) Kilogram _____ 4) Milliliter _____ 7) Kilometer _____
2) Meter _____ 5) Millimeter _____ 8) Centimeter _____
3) Gram _____ 6) Liter _____ 9) Milligram _____
Try these conversions, using the ladder method.
1) 2000 mg = _______ g 6) 5 L = _______ mL 11) 16 cm = _______ mm
2) 104 km = _______ m 7) 198 g = _______ kg 12) 2500 m = _______ km
3) 480 cm = _____ m 8) 75 mL = _____ L 13) 65 g = _____ mg
4) 5.6 kg = _____ g 9) 50 cm = _____ m 14) 6.3 cm = _____ mm
5) 8 mm = _____ cm 10) 5.6 m = _____ cm 15) 120 mg = _____ g
Metric Conversion Challenge
kg mL km m mmcm
g L mg
2 5000 160 104000 0.198 2.5
4.8 0.075 65000 5600 0.5 63 .8 560 0.12
Compare using <, >, or =.
16) 63 cm 6 m 17) 5 g 508 mg 18) 1,500 mL 1.5 L
19) 536 cm 53.6 dm 20) 43 mg 5 g 21) 3.6 m 36 cm
<
<
>
>=
=
Length(m) • the distance
between two points
• SI unit is meter (m)
• Instrument used is ruler or meterstick
Volume(cm3 or
mL)• the amount of
space occupied by an object
• SI units for solids is cm3
• SI units for liquids is mL
Volume =the amount of space occupied by an object
Solids LiquidsTool
usedSI Units
Ruler Graduated cylinder
Multiply LxWxHcm3 (cubic centimeters)
mL (milliliters)
Volume• A derived unit (combination of SI units) -for regular shaped solids, L x W x H
(cm3)• Instrument used to measure
volume of a liquid is the graduated cylinder–* To accurately measure the volume of a liquid, your eye must be at the same level as the bottom
of the meniscus (the curved surface of the water).
10 cm
9 cm
8 cm
Volume of regular object length x width x height
_____ X _____ X _____ = _____
Volume of irregularly shaped objects
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water displacement method
Amount of H2O with object = ______
About of H2O without object = ______
Difference = Volume = ______
mL mL
Mass (kg)• Amount of matter in an
object• SI unit is Kg (g if
smaller)• Instrument is a balance
Temperature (K)• How hot/cold something is• SI unit is Kelvin (K)• *0K = -273oC (Absolute Zero)• Conversion to change oC to
Kelvin, add 273 & vice versa
• Instrument is the thermometer
Time (s) • Interval between two
events• SI unit is second (s)• Instrument is stopwatch
or CPO Timer
Density • Mass per unit
Volume of a material• SI unit is derived
for solids g/cm3, for liquids g/mL
• d=m/v, m=d*v, v=m/d
D
M
V
• What does the layering indicate?• Assuming each liquid has a given
volume of 20mL. What is the mass of each of the substances?
Water
Mercury, _______ g/mL
Gasoline
Gold
Ethanol, _______ g/mL
DensityDensity compares the mass of an object to its volume
D = mass = g or g volume mL cm3
Note: 1mL = 1cm3
Learning Check D1Osmium is a very dense metal. What is its density in g/cm3 if 50.00g of the metal occupies a volume of 2.22cm3?
1) 2.25 g/cm3
2) 22.5 g/cm3
3) 111 g/cm3
Solution 2) Placing the mass and volume of the osmium metal into the density setup, we obtain
D = mass = 50.00 g = volume 2.22 cm3
= 22.522522 g/cm3 = 22.5 g/cm3
Volume DisplacementA solid displaces a matching volume of water when the solid is placed in water.
33 mL25 mL
Learning Check What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 1) 0.2 g/cm3 2) 6 g/m3 3) 252 g/cm3
25 mL 33 mL
Solution 2) 6 g/cm3
Volume (mL) of water displaced = 33 mL - 25 mL = 8 mL
Volume of metal (cm3) = 8 mL x 1 cm3 = 8 cm3
1 mLDensity of metal =
mass = 48 g = 6 g/cm3
volume 8 cm3
• Importance: to ensure the accuracy of our measurements– To make sure we tell others only what we
actually know based on our equipment and it’s limitations
• Accuracy- measure of how close a measurement comes to the actual or true value
• Precision- measure of how close a series of measurements are to one another
Signigicant Figures: Why do they matter?
Significant Figures
GUESS • G= Given, identify the given
information• U= Unknown, identify the unknown,
what are you trying to solve for?• E= Equation, what equation should you
use to solve the problem?• S= Substitute the numbers in for the
letters in the equation• S= Solve, plug in the calculator, chug
get an answer….don’t forget the
units!