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EXPERIMENTS

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					SCIENTIFIC METHOD
 1. FACT : An observable event; indisputable evidence which does
 not explain but simply is.

 2. HYPOTHESIS: A guess to try to explain an observation.

 3. EXPERIMENT: A systematic exploration of an observation or
 concept.

 4. THEORY: An explanation of the facts; it can be proven by
 experiment and it confirms an hypothesis.

 5. LAW: A theory which has undergone rigorous experimentation
 and no contradiction can be found.
 Note:     MODEL: A visual or mathematical device or method used to demonstrate a
 theory or concept.
      Scientific Method

    Observation of an event or object


                    A question


                   A Hypothesis


                  Experimentation


        Theory                    New hypothesis


further experimentation      Developement of new
                          experimentation and theory


         LAW
          EXPERIMENTS

In ancient Greece philosophers, like Aristotle,
did very little physical experimentation. Mental
exercises were the preferred method for solving
problems.

SCIENTIFIC METHOD depends on
experimentation therefore the ability to make
measurements is vital when using scientific
method.
       ACCURACY vs. PRECISION
   Accurate & precise       inaccurate but precise




   inaccurate & imprecise
                MEASUREMENTS
                         Significant Figures
1. All nonzero numbers are significant figures.

2. Zero’s follow the rules below.
      Zero’s between numbers are significant.
                   30.09 has 4 SF
      Zero’s that precede are NOT significant.
                   0.000034 has 2 SF
      Zero’s at the end of decimals are significant.
                   0.00900 has 3 SF
      Zero’s at the end without decimals are ambiguous.
                   4050 has either 4 SF or 3 SF
                   MEASUREMENTS
                  Significant Figures & Calculations
Significant figures are based on the tools used to make the
measurement. An imprecise tool will negate the precision of the other
tools used. The following rules are used when measurements are
used in calculations.

Adding/subtracting
       The result should be rounded to the same number of
decimal places as the measurement with the least decimal
places.
Multiplying/dividing
       The result should contain the same number of
significant figures as the measurement with the least
significant figures.
                MEASUREMENTS
               Significant Figures & Calculations
Adding/subtracting
     345.678                    0.07283
     + 12.67                   -0.0162789

     358.35                       0.05655
Multiplying/dividing

            12.0340 x 3.98 =      47.9
            98.657 / 43 =   2.3
               MEASUREMENTS
                        Scientific Notation
Many measurements in science involve either very large
numbers or very small numbers (#). Scientific notation
is one method for communicating these types of
numbers with minimal writing.


   GENERIC FORMAT:                # . # #… x 10#

A negative exponent represents a number less than 1
and a positive exponent represents a number greater
than 1.
            6.75 x 10-3 is the same as 0.00675
              6.75 x 103 is the same as 6750
                  MEASUREMENTS
                           Scientific Notation
Give the following in scientific notation (or write it out)
with the appropriate significant figures.
       1. 528900300000 = 5.289003 x 1011

                                        -12
      2. 0.000000000003400 = 3.400 x 10

      3. 0.23 =   2.3 x 10-1

      4. 5.678 x 10-7 = 0.0000005678

      5. 9.8 x 104 =   98000
      PRACTICE PROBLEMS #1
Show your work for the following questions on the back. Always give the
correct significant figures.


1. Express each of the following numbers in scientific notation & 3
significant figures.
         A) 3445490087      3.45 x 109
                             _______
                                                              8.77 x 10-3
                                               C) 0.008768 _______

                        8.24 x 10-7
        B) 0.0000008243 _______                                   D) 23560 2.36 x 104
                                                                             _______

                          4.98 x 10                     -4
2. 0.003496 - 0.002998 = ________________

                                     - 3.56 x 10-2
3. (4.36-5.62) / (32.98 + 2.4) = ______________________

                                                   1.1 x 10 -10
4. 8.453 x 10- 43 / 7.7 x 10-33 = ________________

5. [(56.7 x   10-6)   (32 x   1011)]5   / (5.6 x   1017)1/2
                                                                 2.6 x 1032
                                                              = __________
  GROUP STUDY PROBLEM #1
Show all work for the following questions on the back page. Always give the correct
significant figures.
1. What is the scientific method?
2. Describe the difference between accuracy and precision.
3. Explain why tasting chemicals during an experiment is not a safe
practice?
4. Express each of the following numbers in scientific notation.
       a) 0.0404         _______       b) 0.0081 _______
       c) 40.0           _______ d) 2900000 _______
       e) 0.0000055 _______ f) 40300                  _______
6. (452 x 6.2) / 14.30 = ______________________
7. 98.78564 - 97.9299 = ________________
8. 6.022 x 1023 / 1.9 x 10-19 = ________________
9. ( 0.3 - 0.09) / (4.3 x 10-3 + 7.232 x 10-4) = ____________
10. [(2.4 x 1012) (5.78 x 10-31)]3 / (2.965 x 1014)1/2 = __________

				
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