Sponge: List five scientists you saw in the Mechanical Universe film.

Sponge: List five scientists you saw in the Mechanical Universe film.

Physical Science the study of the physical universe.

The two main branches are physics and chemistry.

These two overlap; the main difference is that physics always deals with the concept of energy.

The major areas within Physics are:

• mechanics,

• thermodynamics,

• waves,

• optics,

• electricity and magnetism,

• relativity, and

• nuclear physics.

Scientific MethodLAWS-describe the relationships between various phenomena

•Boyle’s Law

•Charles’ Law

•Cole’s Law

Scientific Law-expressed by words

Laws in physics-expressed by math equations

THEORY-reasonable explanation of observed events that are related.

Theories often involve models.

e.g. Atomic Theory

Democritus’ ModelThomson’s ModelRutherford’s ModelBohr’s ModelElectron Cloud Model

Experiments test theories.

Hypotheses & Investigations

Five StepsProblemResearchHypothesis - extends thinking beyond known facts

ExperimentConclusions

Certainty in science

One should always question the validity of scientific Laws, Theories, or Hypotheses.

METRIC SYSTEM - uses a decimal basis for multiples and fractions of the basic units of measure.

International System of UnitsThe SI system(Systeme International d’Unites)

Units of measure are used to describe physical quantities.e.g. the meter is the unit of length

Seven fundamental units of measure:

• 1. length meter

• 2. mass kilogram

• 3. time second

• 4. electric current ampere

• 5. temperature kelvin

• 6. amount of substance mole

• 7. luminous intensity candela

Combinations of these units are used to measure other physical quantities.(e.g. mass density)These are called derived units.

Modern metric system often called the MKS system.(meter, kilogram, second)

METERStandard 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)

KILOGRAMMass of the standard kilogram. Only measure that still is a natural object.

FORCE AND WEIGHTNewton is the accepted unit.Force needed to accelerate a one kilogram mass by one m/s2.

THE SECONDone second = 9 192 631 770 vibrations of cesium-133 atoms.

1 ml H2O = 1 cm3 H2O = 1 g H2O heat required to change temp of 1 g liquid H2O 1° centigrade (Kelvin) is 1 calorie

The metric measures are related around liquid water.

It is important to indicate the degree of uncertainty in measurements so far as it is known.

ACCURACY - the closeness of a measurement to the accepted value for a specific physical quantity.

absolute error- actual difference between the accepted value and the measured value.

Ea = |O - A|,

where

Ea is the absolute error, O is the observed value, and A is the accepted value.

Relative Error - expressed as a percentage. (often called percentage error)

Er = (Ea / A) x 100%

where

Er is the relative error, Ea is the absolute error, and A is the accepted value.

PRECISION - the agreement among several measurements that have been made in the same way.

Precision is expressed in terms of DEVIATION.

Absolute deviation-difference between a single measured value and the average of several measurements made in the same way.

Relative Deviation-the percentage average deviation of a set of measurements.

Significant Figures - Those digits in a number that are known with certainty plus the first digit that is uncertain.

RULES:1. all nonzero figures are significant

112.6 ____ sig figs

RULES:1. all nonzero figures are significant

112.6 Four sig figs

2. All zeros between nonzero figures are significant

108.005____sig figs

2. All zeros between nonzero figures are significant

108.005 Six sig figs

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

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

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

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

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

5. All zeros right of a decimal point and following a nonzero figure are significant.

0.07080 ____ sig figs

20.00 _____ sig figs

5. All zeros right of a decimal point and following a nonzero figure are significant.

0.07080 Four sig figs

20.00 _____ sig figs

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

6. Addition and subtraction : rightmost sig fig in a sum or difference is leftmost point of one of the initial measurements.

13.05309.2

+ 3.785 326.035

13.05309.2

+ 3.785 326.035

13.05309.2

+ 3.785 326.0

7. Multiplication and division. Product or quotient cannot have any more sig figs than the least precise factor.

3.54 • 4.8 • 0.5421= 9.211 363 2

3.54 • 4.8 • 0.5421= 9.211 363 2

3.54 • 4.8 • 0.5421= 9.211 363 2

3.54 • 4.8 • 0.5421=

9.2

RoundingIf 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.

SCIENTIFIC NOTATIONM • 10nM 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.

Order of magnitude.

numerical approximation to the nearest power of ten.

DATA, EQUATIONS, GRAPHS,DIMENSIONAL ANALYSIS.

Scalar quantities.quantities expressed by single numbers with appropriate units. Vector quantities.Quantities that require magnitude and direction.Usually depicted by arrows.

Two vectors that act on the same point are called components.

A single resultant can be found from these components.Algebraic methods, the parallelogram method, and trigonometric methods can be used to find the resultant.

RULES OF PROBLEM SOLVING

1. Carefully find what is being asked. Write down all given data.

2. Write down all the symbols and units for the quantities called for.

3. Write down the basic equation relating the known and unknown quantities.

4. Solve for the unknown quantity to find the working equation.

5. Substitute the given data into the working equation.

6. Perform the mathematical operations with the units alone.Unit analysisDimensional analysis

7. Perform the math

sig figs!!!!

8. Check the answer for reasonableness

8. Check the answer for reasonableness

8. Check the answer for reasonableness

9. Review the entire solution.