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Sponge: List five scientists you saw in the Mechanical Universe film.
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Physical Science the study of the physical universe.
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The two main branches are physics and chemistry.
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These two overlap; the main difference is that physics always deals with the concept of energy.
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The major areas within Physics are: mechanics, thermodynamics, waves, optics, electricity and magnetism, relativity, and nuclear physics.
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Scientific Method LAWS-describe the relationships between various phenomena
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Boyle’s Law Charles’ Law Cole’s Law
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Scientific Law- expressed by words Laws in physics- expressed by math equations
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THEORY- reasonable explanation of observed events that are related.
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Theories often involve models. e.g. Atomic Theory Democritus’ Model Thomson’s Model Rutherford’s Model Bohr’s Model Electron Cloud Model
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Experiments test theories.
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Hypotheses & Investigations Five Steps Problem Research Hypothesis - extends thinking beyond known facts Experiment Conclusions
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Certainty in science One should always question the validity of scientific Laws, Theories, or Hypotheses.
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METRIC SYSTEM - uses a decimal basis for multiples and fractions of the basic units of measure.
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International System of Units The SI system (Systeme International d’Unites)
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Units of measure are used to describe physical quantities. e.g. the meter is the unit of length
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Seven fundamental units of measure: 1. length meter 2. masskilogram 3. timesecond 4. electric currentampere 5. temperaturekelvin 6. amount of substancemole 7. luminous intensitycandela
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Combinations of these units are used to measure other physical quantities. (e.g. mass density) These are called derived units.
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Modern metric system often called the MKS system. (meter, kilogram, second)
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METER Standard meter was a metal bar until 1960. Now 1 meter = the distance light travels in a vacuum in 1/299 729 458th of a second. (speed of light is no longer subject to revision)
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KILOGRAM Mass of the standard kilogram. Only measure that still is a natural object.
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FORCE AND WEIGHT Newton is the accepted unit. Force needed to accelerate a one kilogram mass by one m/s 2.
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THE SECOND one second = 9 192 631 770 vibrations of cesium-133 atoms.
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1 ml H 2 O = 1 cm 3 H 2 O = 1 g H 2 O heat required to change temp of 1 g liquid H 2 O 1° centigrade (Kelvin) is 1 calorie
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The metric measures are related around liquid water.
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It is important to indicate the degree of uncertainty in measurements so far as it is known.
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ACCURACY - the closeness of a measurement to the accepted value for a specific physical quantity.
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absolute error- actual difference between the accepted value and the measured value.
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E a = |O - A|, where Ea is the absolute error, O is the observed value, and A is the accepted value.
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Relative Error - expressed as a percentage. (often called percentage error)
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E r = (E a / A) x 100% where E r is the relative error, E a is the absolute error, and A is the accepted value.
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PRECISION - the agreement among several measurements that have been made in the same way.
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Precision is expressed in terms of DEVIATION.
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Absolute deviation- difference between a single measured value and the average of several measurements made in the same way.
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Relative Deviation- the percentage average deviation of a set of measurements.
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Significant Figures - Those digits in a number that are known with certainty plus the first digit that is uncertain.
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RULES: 1. all nonzero figures are significant 112.6 ____ sig figs
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RULES: 1. all nonzero figures are significant 112.6 Four sig figs
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2. All zeros between nonzero figures are significant 108.005____sig figs
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2. All zeros between nonzero figures are significant 108.005 Six sig figs
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3. Zeros right of a nonzero figure, but left of understood decimal point, are not significant unless indicated. 109 000 _____ sig figs _ 109 000 _____ sig figs
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3. Zeros right of a nonzero figure, but left of understood decimal point, are not significant unless indicated. 109 000 Three sig figs _ 109 000 _____ sig figs
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3. Zeros right of a nonzero figure, but left of understood decimal point, are not significant unless indicated. 109 000 _____ sig figs _ 109 000 Five sig figs
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4. Zeros to the right of a decimal point but to the left of a nonzero figure are not significant. Zero to the left of decimal point is never significant. 0.000 647 _____sig figs
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4. Zeros to the right of a decimal point but to the left of a nonzero figure are not significant. Zero to the left of decimal point is never significant. 0.000 647 Three sig figs
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5. All zeros right of a decimal point and following a nonzero figure are significant. 0.07080 ____ sig figs 20.00 _____ sig figs
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5. All zeros right of a decimal point and following a nonzero figure are significant. 0.07080 Four sig figs 20.00 _____ sig figs
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5. All zeros right of a decimal point and following a nonzero figure are significant. 0.07080 Four sig figs 20.00 Four sig figs
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6. Addition and subtraction : rightmost sig fig in a sum or difference is leftmost point of one of the initial measurements.
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13.05 309.2 + 3.785 326.035
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13.05 309.2 + 3.785 326.0
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7. Multiplication and division. Product or quotient cannot have any more sig figs than the least precise factor.
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3.54 4.8 0.5421= 9.211 363 2
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3.54 4.8 0.5421= 9.2
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Rounding If the figure to be dropped is 4 or less, the preceding figure is not changed. If the figure to be dropped is 5 or more, the preceding figure is raised by 1.
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SCIENTIFIC NOTATION M 10n M is a number greater than or equal to 1, but less than 10. n is the number of places the decimal point has been shifted. Moved left, n is pos. Moved right, n is neg.
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Order of magnitude. numerical approximation to the nearest power of ten.
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DATA, EQUATIONS, GRAPHS, DIMENSIONAL ANALYSIS.
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Scalar quantities. quantities expressed by single numbers with appropriate units. Vector quantities. Quantities that require magnitude and direction. Usually depicted by arrows.
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Two vectors that act on the same point are called components.
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A single resultant can be found from these components. Algebraic methods, the parallelogram method, and trigonometric methods can be used to find the resultant.
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RULES OF PROBLEM SOLVING
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1. Carefully find what is being asked. Write down all given data.
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2. Write down all the symbols and units for the quantities called for.
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3. Write down the basic equation relating the known and unknown quantities.
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4. Solve for the unknown quantity to find the working equation.
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5. Substitute the given data into the working equation.
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6. Perform the mathematical operations with the units alone. Unit analysis Dimensional analysis
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7. Perform the math sig figs!!!!
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8. Check the answer for reasonableness
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9. Review the entire solution.
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