Transcript science skills and characteristics

What is Science?
-the organized body of knowledge about the
Universe derived from observation and
experimentation carried out to determine the
principals underlying what is being studied
Branches of Science
Natural science
Biological sciences
anatomy
virology
Earth sciences
geology
physics
botany
zoology
Physical sciences
chemistry
meterology
Scientific Method
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Question why or how something happens
Research Existing Data
Form a hypothesis (expected answer)
Experiment
Collect data (information)
Draw a conclusion
Contemplate opportunities for future study
DATA
• Data must be collected to support or refute
the hypothesis:
• Data may be
Quantitative: Numeric Quantity
Qualitative: Descriptive in nature
The Scientific Method allows
science to be universal. Why?
• Language Barriers exists between
countries (English Speakers vs. NonEnglish Speakers)
• Measurement Standards (distance can be
measured in feet or meters )
• This standardization allows for scientists
around the world to share ideas.
Setting up a valid experiment:
Scientific Method Style
• Make an observation: Plants seem to grow
best with a certain amount of moisture.
• State the question: How does water affect the
growth of plants?
• Form a hypothesis: If I give a plant more water,
then it will grow taller.
• Set up the experiment: One control group and
one experimental group.
• Collect data: Record plant growth and water
distribution and graph the data.
• Repeat: Redo the experiment to disprove
results.
Variables in an experiment
• Independent variable: the portion of the experiment that
the scientist actually controls or changes (the cause / the
if) -always graphed on the x axis
• Dependent variable: the portion of the experiment that
changes on its own (the effect / the then) – always
graphed on the y axis
Dependent
Variable
Y axis
Independent
Variable
X axis
Experimental Group
Full sun and 25*C
Control Group
Full sun and 25*C
A
B
Plant
A
B
C
D
water added daily
10mL
15mL
20mL
25 mL
C
growth
0 cm
5 cm
10 cm
15cm
D
Growth vs. Water for Plants
15
10
Growth
(cm)
5
0
0
5
10
15
20
25
Water added
(mL)
A graph of this shape supports the hypothesis that
more water increases plant growth.
Growth vs. Water for Plants
15
10
Growth
(cm)
5
0
0
5
10
15
20
25
Water added
(mL)
A graph of this shape does not support the hypothesis that
more water increases plant growth. You may have
over-watered the plant and it wilted.
Significant Figures
• the number of digits in a measurement
that are known with certainty
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• 4 Rules for finding significant figures
• Rules for Adding / Subtracting Sig Figs
• Rules for Multiplying / Dividing Sig Figs
Rule 1 for determining
Significant Digits
• All non-zero numbers are significant
1.27m has 3 sig figs
2278s has 4 sig figs
98 feet has 2 sig figs
Rule 2 for determining
Significant Digits
• Any zero that is between two non-zero
numbers is significant.
105m has 3 sig figs
190003cm has 6 sig figs
2006 mi has 4 sig figs
Rule 3 for determining
Significant Digits
• Any zero to the right of a decimal is
significant.
23.30s has 4 sig figs
0.450m has 3 sig figs
29.000m has 5 sig figs
Rule 4 for determining
Significant Digits
• A zero that has the sole purpose of placing
a decimal is not significant.
20 m has 1 sig fig
200 mi has 1 sig fig
0.0092 m has 2 sig figs
Addition and Subtraction for
Significant Digits
• With addition and subtraction, limit your
answer to the number of decimal places
held by the measurement containing the
least number of decimal places.
2.50cm + 9.0 cm = 11.5 cm (not 11.50 cm)
1/100
Decimal
Place
1/10
Decimal
Place
1/10
Decimal
Place
35.05g - 5.0g = 30.05g =30.1g
1/100
Decimal
Place
1/10
Decimal
Place
1/10
Decimal
Place
Rounding:
0-4 = Round down
5-9 =Round up
Multiplication and Division for
Significant Digits
• When multiplying or dividing
measurements, your answer should
contain the same of significant digts found
in the measurement with the least number
of significant digits.
3.0 cm X 2 cm = 6 cm2 (not 6.0 cm2)
2 sig figs
1 sig fig
1 sig fig
50.00 g / 2 moles = 25 g/mole = 30 g/mole
4 sig figs
1 sig fig
2 sig figs
Answer must also have 1 sig fig
Accuracy vs. Precision
• Accuracy
– The closeness of a
measurement to an
accepted value.
2 of 3 are accurate.
• Precision
– The closeness of
a group of
measurements to each
other.
Accurate?No.
Very precise. 3 are
grouped together.
Measurement Examples
• Accepted Value: 10.0 m
• Measurements: 10.0, 9.9, 10.0, 9.9
– Good accuracy, Good precision
• Measurements: 11.4, 11.5, 11.5, 11.6
– Poor accuracy, Good precision
• Measurements: 8.9, 11.9, 12.5, 9.2
– Poor accuracy, Poor precision.
Percent Error
• How far your measurements are away
from an accepted value.
• You generally want 10% error or less. This
would be equivalent to making a 90 on a
test.
• Formula:
• % Error = | observed value – accepted value|
accepted value
X 100%
Percent Error Example
• The actual density of steel is 7.8 g/cc. In lab you
measure the density as 9.2 g/cc. What is the
percent error of your measurement?
• % error = | 9.2 g/cc – 7.8 g/cc | = 0.179
7.8 g/cc
Convert this number to a % by
multiplying it by 100.
0.179 X 100 = 17.9 % = 18 %
Follow sig fig rules to round.
Measurements
• The SI System (International System)
– Based on the metric system, the powers of
10, and uses prefixes.
– World-wide use.
– Also known as the KMS system.
• Kilogram, meter, second
– Mass will be measured in kilograms with a triple beam
balance.
– Length will be measured in meters using a ruler.
– Time will be measured in seconds using a stopwatch.
Prefixes for the Metric System
1.) Move up or down depending
upon conversion of units.
2.) Count steps each way.
3.) k, h, da, d, c, m
kilo
1000
hecto
100
deca
10
Base units: gram, liter, meter,
second
base
1
deci
.1
centi
.01
milli
.001
Conversion Example:
• Convert 256 cm to meters.
meter
1. Start on centimeter
2. Count steps to meter.
3. Move the decimal 2 places
to the left.
4.) 2.56 m
decimeter
centimeter
millimeter
Scientific Notation
• A way to express very large or small numbers.
• Formula:
Z X
10n
• Z is the mantissa. It is a number between 1 and
10. The number of significant figures is included
in the mantissa.
• n is a power of 10 that represents the direction
and number of spaces that the decimal is moved
in order to arrive at the Z number.
• Positive n moves the decimal to the right. Negative n moves
the decimal to the left.
Example
• Convert 207,000 to scientific notation.
2.07 X 105
1.) write down all sig figs
2.) place decimal so the number is
between 1 and 10
3.) count placeholders and
record them as an exponent
• Convert 0.00101 to scientific notation.
1.01 X 10-3
Relationship of Science and
Technology
• Wheel of knowledge:
Scientific Theory vs. Law
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A scientific law is simply an
observation about nature: Ex: What
goes up, must come down”
A scientific theory is an explanation of
an observation. Ex. “The bending of
space causes gravitation”
Theories are:
-Simple and clear
-Testable
-Repeatable