Transcript Chapter 1: Science Foundations of Science

Chapter 1: Science
Foundations of Science
1. What is Science?
• Science = A system of knowledge
based on facts or principles
–Observation = gathered data that
can be seen, heard, tasted,
smelled, or touched
–Inference = a logical interpretation
based on prior knowledge or
experience
• Branches
–Social sciences
–Natural science (Biology, Physical
science, Earth science)
2. Scientific theories and laws
• Science is an ongoing process;
information improves and changes
• Theory = a tested, possible explanation
of a natural event
–Simple and clear explanation
–Experiments must be repeatable
–Theory can be used to predict things
• Law = a summary of an observed natural
event
3. The Scientific method
• Sci. Method = A series of logical steps to follow
in order to solve problems
– Observe
– Formulate a question
– Collect data
– Form a hypothesis = Proposed explanation of
observed events
– Conduct experiment
– Collect data
– Draw conclusions
• Control = Condition in experiment that is
kept the same
• Variable = Anything that can change in an
experiment
Metric System
1. What is it?
• A system of measure based on water that
converts in increments of 10s.
• 10 these = 1 those
10 those = 1 that
10 that = 1 them
• Advantage: easily converted and used across
the world
• What are some of the things that we measure?
– Height
– Length
Volume
Weight
2. Metric Math
• Prefixes
King
Henry
Died
By
drinking
chocolate
milk
Kilo
Hecto
Deca
Base
deci
centi
milli
0.001
0.01
0.1
1
10
100
1000
• Each prefix indicates ten times more than the previous
• With each conversion of unit (change in prefix) you will
multiply by 10 or divide by 10
– Moving right x 10
– Moving left
÷ 10
• each time I multiply by 10 watch what happens
to the decimal
– 1 x 10 = 10.
– 20 x 10 = 200.
– 300 x 10 = 3000.
• the opposite happens when I divide by 10
– 3000 ÷ 10 = 300
– 200 ÷ 10 = 20
– 10 ÷ 10 = 1
The decimal slides one place with each x or ÷ by 10,
so use the simple sliding method
• Steps of Metric conversion
– 1. draw your metric line: KHDbdcm
– 2. figure out which direction you will be moving
– 3. determine how many times the decimal has to
slide between the units
– 4. move the decimal in the given number
– 5. Check to make sure the answer makes sense
• Example 1: 6 Km = _________________m
– 1. KHDbdcm
– 2. K.HDb.dcm (starting at kilometer and ending at
meter)… moving right
– 3. decimal moves three spots
– 4. 6 Km = 6000 m
– 5. Yes, there are more meters in a kilometer
• Practice:
– 526 m = 52600 cm
– 8000 cm = 0.08 Km
– 0.40 m = 400 mm
– 0.0003 Km = 0.3 m
3. Scientific Notation
• Does anyone know what a googol is?
– 1 followed by 100 zeros
– Would you write it out?
Scientific notation = a method of writing or
displaying large numbers in a simple format
by sliding the decimal and accounting for the
slides by multiplying by ten
• Number (1 to 9.9) x 10exponent
234 becomes 2.34
each slide of decimal = x 10 = exponent
• A googol is 1 x 10100
• Practice:
– 2500 = 2.5 x 103
– 2503000 = 2.503 x 106
– 0.00002 = 2 x 10 -5
– .0002500030 = 2.50003 x 10-4
Accuracy vs. Precision
• The dictionary definitions of these two
words do not clearly make the distinction
as it is used in the science of
measurement.
1. Accurate : "capable of providing a correct
reading or measurement."
• In physical science it means 'correct'.
• A measurement is accurate if it correctly
reflects the size of the thing being
measured.
2.Precise means "exact, as in performance,
execution, or amount. "
• In physical science it means "repeatable,
reliable, getting the same measurement
each time."
• We can never make a perfect
measurement.
• The best we can do is to come as close as
possible within the limitations of the
measuring instruments.
• For example a metric ruler which has
millimeter marks has a least count of 1
mm or 0.1 cm. and when properly used it
can make more precise measurements
than one with centimeter marks.
• It is "six point something": more than six
but less than seven. With certainty we can
say it is in the range of 6 to 7. Exactly
where in that range is an estimate. We
might guess it is 40% of the way, just less
than halfway, between 6 and 7 or 6.4.
• It is clear that our estimate was close, but the
measurement still does not align with a mark.
Not only that, but we are having trouble reading
the marks now because they are so fine. Now
we can estimate with a higher precision that the
measurement is 6.39, although you might say
that it is 6.38 or even 6.40. Whatever it is, your
best guess is 'correct' although it is not certain.
Density
Density is a physical property of matter
- the mass per unit volume of a substance
- how much “stuff” is in a certain “space”
- density remains the same for any volume
of a pure substance
If something is known as being “light”… it probably
has a small density
Common densities
Substance
Density g/cm3
Water (l)
1.00
Water (s) – ice
0.92
Lead
11.3
Air (mixture)
0.00129
Density Math – density is calculated by
dividing the object’s mass by its volume.
- density = mass =
g
=
g
volume
cm3
ml
Example 1: If a box has a volume of 3.0 cm3
and a mass of 9.0 g, what is its density?
Example 2: If a liquid has a volume of 200
cm3 and a mass of 800 g, what is its
density?
Gasoline has a density of 0.7 g/mL. If your
4-wheeler uses 1,000 mL of gas doing
donuts in the lawn, how much lighter is
your ride (what mass of gas was used)?