welcome to physical science

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!