physics introduction. what is science - systematic knowledge of the physical or material world...

PHYSICSIntroduction

What is Science

- systematic knowledge of the physical or material world

gained through observation and experimentation.

What is Physics?

- the science that deals with matter, energy, motion, and force.

- The Rules of Nature.

•Hypotheses – tentative and testable statements that must be capable of being supported or not supported by observational evidence. To be accepted as a good hypothesis, there must exist a test or experiment to try and prove it wrong.

•Theory - based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations , but may be subject to change as new areas of science and new technologies are developed

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

LAWS-describe the relationships between various phenomena

Independent variable

– factor that is adjusted by the experimenter to see what effect the change has on the dependent variable

Dependent variable

–  factor whose value changes because of a change in the independent variable

Inference

– a  reasonable conclusion or possible hypotheses based on observations

Observation

- A conclusion or data gathered, based upon directly observing something.

- Observations can be made with eyes, ears, nose, or touch.

Distance

•The entire linear distance traveled despite side trips

Displacement

•The distance between points “A” and “B”.

• “As the crow flies”

From A to B = 250 m From A to B = 40 m

Point A

Point B

Point A

Point B

•Boyle’s Law

•Charles’ Law

•Cole’s Law

Experiments test theories.

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 Method

Five StepsState ProblemResearch itHypothesis - extends thinking beyond known facts

ExperimentDraw Conclusions

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 Units =The SI system

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

FORCE AND WEIGHTNewton is the accepted unit.Force needed to accelerate

a one kilogram mass by one m/s2.

% Error – Little Number / big number X 100

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

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

Is this Accurate, Precise, Both, or Neither

Is this Accurate, Precise, Both, or Neither

Is this Accurate, Precise, Both, or Neither

Is this Accurate, Precise, Both, or Neither

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.

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

RULES OF PROBLEM SOLVING

1. Carefully find what is being asked. Write down all given data. (“Make a shopping list”)

2. Write down all the symbols and units for the numbers.

3. Go shopping for an equation that matches the data in your shopping list.

4. Rearrange the formula to solve for your unknown variable.

5. Put your data into the working equation.

6. Calculate an answer. Do not involve the units.

7. Check the answer for reasonableness

7. Check the answer for reasonableness

7. Check the answer for reasonableness

8. Review the entire solution.