Measurement%20

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Measurement the Standard International Units

• Scientific Method
• Metric System
• Measurement
• Density
• Scientific Notation
• Conversions Dimensional Analysis
• Graphing

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What is Science?

• I. Science from Curiosity
• A. Science involves asking questions about
  nature and then finding ways to answer them.
• B. This process does not happen by itself- it
  is driven by the curiosity of scientists.

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• C. Science- a system of knowledge and the
  methods you use to find that knowledge.
• D. Science begins with curiosity and often ends
  with discovery.
• 1. Curiosity provides questions but is
• seldom enough to achieve scientific
• results.

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• 2. Methods such as observing and measuring
  provide ways to find the answers.
• 3. Observations can be
• a. qualitative- descriptive
• b. quantitative- numerical

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II. Science and Technology

• A. Technology- the use of knowledge to solve
  practical problems.
• 1. The goal of science is to expand or gain
• knowledge
• 2. The goal of technology is to apply that
• knowledge

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• B. Science and technology are interdependent.
  Advances in one lead to advances in the other.
• C. Look at figure 2 on page 3 and think about how
  phones have changed over the last 100 years.

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• 1. Do you regularly use a phone with a rotary
  dial or push buttons?
• 2. How do you think phones have changed between
  1955 and 2003?
• 3. What is the difference between cellular and
  cordless phones?
• 4. How have cell phones increased the area in
  which phone service is available?

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III. Branches of Science

• A. Science is divided into social science (such
  as anthropology and psychology) and natural
  science.
• B. Natural science is generally divided into
  three branches.
• 1. Physical Science- focuses on nonliving
  things and includes physics and chemistry.

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• 2. Earth and Space science- applies physics
  and chemistry to the study of Earth. In modern
  days this also includes the study of space. The
  major sciences include geology, astronomy,
  meteorology and oceanography.

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• 3. Life Science- includes the study of living
  things. It is also known as biology and includes
  botany, zoology, ecology and genetics.

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• C. The problem with subdividing science into
  different areas is that there is often overlap
  between them.
• 1. Biology also includes chemistry
• (biochemistry)
• 2. Much of physics includes biology
• (biophysics)

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IV. The Big Ideas of Physical Science

• A. Physical science studies some of the basic
  rules of science.
• 1. Space and time- The universe is both very
  old and very big.
• a. It is about 13.5 billion years old.
• b. It is about 700 million billion billion
  meters in diameter.

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• 2. Matter and Change- A very small amount of
  the universe is matter.
• a. Matter has volume and mass and usually
• takes the form of a solid, liquid or
  gas.
• b. Matter is made up of building blocks
• called atoms.

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• 3. Forces and Motion- Forces cause changes in
  motion.
• a. If you push on something that is sitting
• still, it will move.
• b. If you push on something that is already
• moving, you will change its motion.

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• 4. Energy- Energy exists in many forms.
• a. Moving objects have kinetic energy.
• b. Energy exists in matter itself and matter
• can be changed into energy.
• B. Keep in mind that some more rules are still
• waiting to be discovered.

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Using a Scientific Approach

• I. Scientific Methods
• A. Scientific Method- an organized plan for
  gathering, organizing, and communicating
  information
• 1. Can be used by anyone, not just scientists
• 2. The goal is to solve a problem or better
• understand an observed event.

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• B. Five Steps to the scientific method
• 1. State the Problem
• a. What do you want to know?
• b. Should be specific

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• 2. Gather information/do research
• a. Make observations and ask questions
• b. An observation is information you
• obtain through your senses
• c. Repeatable observations are known as
• facts

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• 3. Make a hypothesis
• a. Make an educated guess or possible
• solution to the problem
• b. For a hypothesis to be useful, it must be
  
• testable

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• 4. Experiment or test your hypothesis
• a. Observe, measure, test
• 1) Variable- any factor that can change
• a) manipulated variable- causes a
• change in another
• b) responding variable- changes in
  response
• the manipulated variable

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• 2) Controlled experiment- an experiment in
• which only one variable (the
• manipulated) is deliberately changed at a
• time.
• b. Record and analyze the data

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• 5. Draw a conclusion
• a. Decide whether or not your data
• supports your hypothesis
• b. Is your hypothesis correct or incorrect?
• If the hypothesis is not correct you
  must
• propose a new one.

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• C. Developing a Theory
• 1. Scientific theory- a well-tested
• explanation for a set of observations or
• experimental results.
• 2. A theory is never proved
• 3. Atomic theory and kinetic theory

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II. Scientific Laws

• A. Scientific Law- a statement that
• summarizes a pattern found in nature.
• B. Newtons law of gravity.
• C. Laws describe an observed pattern in
• nature without attempting to explain it.
• D. The explanation is provided by a
• theory.

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III. Scientific Models

• A. Model- a representation of an object or
• event
• B. Include street maps, globes, and computer
• models
• C. Models make it easier to understand things
  that might be too difficult to observe directly

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• D. Models are continually being tested and
  replaced if the data show that the model is wrong.

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IV. Working Safely in Science

• A. You must follow safety precautions at all
• times.
• B. Study the rules in the safety handbook.
• C. Before starting any lab, read all of the
  instructions.
• D. The most important rule is to follow your
  teachers instructions and the textbook
  directions exactly.

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• E. If you are in doubt, ask your teacher for an
• explanation.
• F. Wash hands thoroughly after every lab.

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Section 1.3

• Measurement

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I. Using Scientific Notation

• A. Scientists often work with very large or very
  small numbers.
• 1. Speed of light 300,000,000 meters per sec
• 2. Speed of snail 0.00086 meters per second

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• B. Scientific Notation
• 1. A way of expressing a value as the
• product of a number between 1 and 10
• and a power of 10.
• 2. Is a shortcut to writing all of the 0s in a
• number.

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• a. 300,000,000 3.0 x 108
• the exponent 8 tells you that the
• decimal point is really 8 places to
  the
• right of the 3

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• b. 0.00086 8.6 x 10-4
• 1) The negative exponent means the
• number is a decimal
• 2) The exponent of a 4 tells you how
• many decimal places there are to the
• left of the 8.6

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• 3. Makes very large or very small numbers
• easier to work with.
• C. Multiplying in Scientific Notation
• 1. Multiply the numbers that appear before
• the multiplication signs.
• 2. Add the exponents.
• 3. Make sure answer is in proper form.

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• D. Example of multiplying
• 1. How far does light travel in 500
• seconds?
• (Speed of light)(time) distance
• (3.0 x 108 m/s)(5.0 x 102 s) distance
• 3 x 5 15
• 8 2 10

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• 2. Answer
• 15 x 1010 m 1.5 x 1011 m
• Remember number before the power of ten must be
  greater than 1 and less than 10.
• If you need to move the decimal to the Left
  Add, or to the Right Subtract (LARS)

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• E. When Dividing in Scientific Notation
• 1. Divide the numbers that appear before
• the exponents
• 2. Subtract the exponents.

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• F. Example of Dividing
• How long will it take for light from the sun to
  reach the Earth?
• Distance/velocity time
• (1.5 X 1011 m)/(3.0 x 108 m/s) time

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• 1.5/3 0.5
• 11-8 3
• Answer is 0.5 x 103 s 5.0 x 102 s

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II. SI Units of Measurement

• For a measurement to make sense, it
• requires both a number and a unit.
• 1. Always use measurements in
• numbers and units so that their
• meaning is clear.

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• 2. Scientists use a set of measuring
• units called SI, or the International
• System of Units.
• 3. By using one system of units,
• scientists can readily interpret one
• anothers measurements.

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• B. Base units and derived units
• 1. Base Units- the 7 metric units on
• which the SI system is based.
• 2. Derived Units- are the additional
• units that come from combinations
• of the base units.

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• 3. Derived units include volume
• (length x width x height) and density
• (mass/volume).

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• C. Metric Prefixes
• 1. Indicates how many times a unit
• should be multiplied or divided by
• ten.
• 2. 9ms 9/1000 s 0.009 seconds

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• 3. 12 km 12 x 1000 m 12,000 m
• 4. Are used in non-metric units as well
• a. gigabyte 1,000,000,000 bytes
• b. megapixel 1,000,000 pixels

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• 5. Conversion Factor- a ratio of
• equivalent measurements that is used
• to convert a quantity expressed in
• one unit to another unit.

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• a. to convert from 8848 m to km
• 8848 m x 1 km 8.848 km
• 1,000 m
• notice that the meter units cancel

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D. The Seven Fundamental Units of Measurement

• Measurement SI Unit
• Length meter (m)
• Mass kilogram (kg)
• Volume liter (L)
• Time second (s)
• Temperature Kelvin (K)
• Amount of Substance mole (mol)
• Electric Current Ampere (A)

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E. Commonly Used Prefixes
Prefix Symbol Meaning Numeric Form Fraction
Kilo - k Thousand 1,000 1,000
Hecto - h Hundred 100 100
Deca - da Ten 10 10
(base unit) m, L, g One 1 1
Deci - d Tenth 0.1 1/10
Centi - c Hundredth 0.01 1/100
Milli - m Thousandth 0.001 1/1,000
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III. Limits of Measurement

• A. Precision the agreement of several
  measurements that have been made in the same way.
  
• Ex Measurements of 1.23, 1.25, 1.21 and 1.24 are
  precise.

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• B. Accuracy the closeness of a measurement to
  the accepted value for a quantity.
• Ex Gravity is measured at 9.81 m/s2

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C. Measurements can be

• C. Measurements can be
• accurate but not precise.
• precise but not accurate.
• both accurate and precise.
• neither accurate nor precise.

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D. Errors of measurement

• Any time you are making a measurement you will
  experience some type of measuring error.
• These errors may occur as
• Instrumental error- caused by faulty, inaccurate
  apparatus
• Personal error- caused by you or your lab partner
• External error- caused by external conditions
  (wind, temperature, humidity)

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E. Measuring Length

1. When measuring length, we will be using a metric
   ruler or meterstick.
2. The numbered divisions are 1 cm divisions.
3. The smallest divisions marked are 1 mm divisions.
   Estimating to the next digit will give 1/10th of
   a millimeter.

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F. Measuring Mass

1. When using an electronic balance, write down all
   numbers printed on the screen.
2. When using a triple beam balance, the mass can be
   measured accurately to 0.01 grams.

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G. Measuring the Volume of a Solid

1. When measuring the volume of a solid object,
   multiply its length x width x height.
2. Typically the volume of a solid is measured in
   either cubic centimeters (cm3) or cubic meters
   (m3).

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H. Measuring the Volume of a Liquid

1. For smaller amounts of liquid, a graduated
   cylinder is used.
2. For larger amounts of liquids, a beaker would be
   used.
3. The most common units used for these types of
   volumes are liters (L) and milliliters (mL).

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I. Measuring Time

1. Many times, we will be using a digital stopwatch
   which are accurate to 1/100th of a second.
2. If a stopwatch with a second hand is being used,
   it will measure to nearest second. In this case,
   an estimated measurement to the nearest 1/2
   second is possible.

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IV. Density

• A. When one speaks of lead as being heavy or
  aluminum as light, one is actually referring to
  the density of these metals.
• B. Density is defined as mass per unit volume.

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C. Calculating Density

• An object with a mass of 10 grams and a volume of
  5 cm3 has a density of 2 g/cm3.

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V. Conversions and Dimensional Analysis or Factor
Label Method

• Not all objects that are measured are in the
  units that are needed.
• The factor label method is a mathematical way to
  convert from the units you have to the units you
  need.
• In order to eliminate the unwanted units, you
  design a ladder-type set up of equalities that
  cancel out the units you no longer want.
• Example How many liters are there in 3650 mL?

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D. Steps of Factor Label

• 1. Write down the number (with units) given in
  the problem on the left side of the paper.
• 2. Write the units you are solving for after an
  equals sign on the right side of the paper.
• 3650 mL L

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• 3. Find an equality relating to the original
  units and write it down in the ladder set up.
  Make sure to put the units that you DO NOT want
  in the denominator. Cross out the units that
  match.
• 3650 mL 1 L L
• 1000 mL

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• 4. Ask yourself if you want the units in the
  numerator. If you dont, repeat steps 3 and 4
  until you get the correct units in the numerator.
• 5. Solve the problem by multiplying the numbers
  in the numerator, then dividing by the numbers in
  the denominator.
• 3650 mL 1 L 3.65 L
• 1000 mL

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Graphing

• A graph is a visual display of information or
  data. The three main types of graphs are pie
  graphs, bar graphs, and line graphs. The type of
  graph used depends on how the information was
  collected and how it is to be presented.

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Pie Graphs

• A pie graph is used to show how some fixed
  quantity is broken down into parts. The circular
  pie represents the total, and the slices
  represent the parts. The slices are usually
  represented as percentages of the total.

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Example of a Pie Graph

• The pie chart below shows the ingredients used to
  make a sausage and mushroom pizza. The fraction
  of each ingredient by weight shown in the pie
  chart below is now given as a percent. Again, we
  see that half of the pizza's weight, 50, comes
  from the crust. Note that the sum of the percent
  sizes of each slice is equal to 100.
  Graphically, the same information is given, but
  the data labels are different. Always be aware of
  how any chart or graph is labeled.

Click here to make your own pie graph
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Bar Graphs

• A bar graph is useful for showing information
  collected by counting. In a bar graph, the bars
  are not connected, and each bar represents a
  different item that is counted.

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Example of a Bar Graph

• The bar chart below shows the weight in kilograms
  of some fruit sold one day by a local market. We
  can see that 52 kg of apples were sold, 40 kg of
  oranges were sold, and 8 kg of star fruit were
  sold.

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Line Graphs

• Line graphs are used to show trends or continuous
  changes in a relationship between different
  objects.

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