Physics Chapter 1 Notes Physics the Science of Energy

1
Physics - Chapter 1 NotesPhysics the Science of
Energy

• Mr. Seaney

2
The Method of Science

• Science Permeates every aspect of daily life
• Science- the search for relationships that
  explain and predict nature.
• Engineering / technology The use of science to
  meet human needs
• Scientific Law A statement that describes the
  relationship between various phenomena. Widely
  accepted and thoroughly tested.
• Theory- A reasonable explanation of observed
  events that are related. Generally accepted and
  widely tested. Often involves models and can be
  used to predict future behavior

3
The Method of Science cont

• Hypothesis- Possible solution to a scientific
  problem.
• All hypotheses, theories, and laws have inherent
  uncertainty. All can be disproved by a single
  crucial experiment.

4
What is Physics?

• The study of energy and its transformations
• Matter Anything that has mass and inertia.
• All matter has specific properties that can be
  measured.
• Mass- amount of material in an object
• Inertia- Property that opposes any change in its
  state of motion
• Mass Density- mass per unit volume
• Energy The capacity to do work
• Potential energy Stored energy based on
  position of object or molecules
• Kinetic Energy Energy based on relative motion
  to an arbitrary stationary point. Earths surface
  is considered to be stationary.
• Law of Conservation of energy energy can be
  changed from one form to another without loss.
• Emc2 - mass and energy can be considered
  equivalent to one another

5
The Scientific Method

• A way to answer questions and solve problems
• Steps in the Scientific Method
• Observation Curiosity about nature
• Question Why or how the event occurs
• Hypothesis Proposed or tentative answer
• Experiment Test with variable control
• Conclusion Analyze data interpret results
• Theory Explains why, allows prediction
• Natural Law Explains how nature behaves

6
Scientific Method Flow Chart
7
Safety in the Laboratory

• Rules Procedures
• Follow teachers and lab directions
• Notify teacher of problems
• Know how to use safety equipment
• Wear safety goggles at all times
• Tie back long hair
• Avoid awkward transfers
• Let hot stuff cool or use tongs / hot mitts
• Carry chemicals defensively
• Dispose of wastes properly
• Clean up after lab

8
Branches of Physics

• Mechanics- motion, forces, work, power
• Thermodynamics - Heat
• Waves- mechanism of energy transfer
• Electricity magnetism Forms of energy
• Nuclear composition and energy Stored in matter.

9
Measurement and Problem Solving

• The Metric System
• International System of units SI
• MKS system in Physics

10
Measurement Continued

• Meter m -Base unit of length distance that
  light travels in 1 299 792 458th of a second.
• Kilogram kg-Unit of mass standard is a natural
  object
• Force and Weight- Unit is newton (N) Kg.m/s2
• Second s- time for 9 192 631 770 vibrations of
  Ce133
• Area and Volume Derived Units (combination of
  base units) cm2 or m2 - area cm3 or m3 -
  volume
• 1dm31liter 1 cm31 ml
• Be careful converting between units

11
Some Derived Units
12
Common Metric Prefixes
13
Uncertainty in Measurement

• Making Measurements
• All Measurements are uncertain
• Every measurement involves estimation
• This uncertainty can be expressed as x where x
  is the smallest measure possible with that
  instrument
• Reliability in measurement
• Precision - Repeatability of measurement
• Accuracy - Nearness to accepted value

14
Accuracy vs. Precision
?
Precise Not Accurate
?
Accurate Not Precise
?
Not Accurate or Precise
?
Accurate And Precise
15
Working with Numbers

• Significant Digits
• Measurements are only as precise as the
  instrument
• Numbers must be rounded to the correct number of
  significant figures
• Atlantic Pacific Rule - If a decimal point is
  present count from the Pacific side starting with
  the first nonzero digit. If a decimal is absent
  count from the Atlantic side starting with the
  first nonzero digit

16
Rules for Significant Figures

• All zeros between nonzero digits are significant
  (count)
• All nonzero figures are significant. (count)
• Zeros to the left of an expressed decimal and to
  the right of a nonzero digit are significant
  (count)
• Zeros to the right of an expressed decimal and
  left of a nonzero digit are not significant
  (dont count)
• Zeros to the right of nonzero digits that are
  right of the decimal are significant (count them)
  
• If there is no expressed decimal all zeros to the
  right of the last nonzero digit are not
  significant (dont count)

17
Practice on Significant Figures
3000
.00105
3.006
1 3000
3 .00105
4 3.006
4020
4020
3 4020
.7000
4 .7000
80.007
80.007 5
.00091
2 .00091
50.
2 50.
18

• II. Significant digits in Calculations
• A. When multiplying or dividing round to the
  least number of significant figures used in the
  operation
• Example 2 X 12 24 round to 20
• B. When adding and subtracting round to the
  fewest decimal places used
• Example 3.02 5.3 1.158 9.478 round to
  9.5
• C. Conversions and exact numbers (counting
  numbers) have infinite significant digits
• Example .0432 km X 1000 m/km 432 m
• D. If several operations are performed dont
  round until the final answer
• E.If the last number is ? 5 Round up or lt 5 round
  down
• III.Scientific Notation useful in working with
  very large or small numbers
• A. Make sure you can convert from and to
  scientific notation ( See worksheets and handout)

19
Error Deviation

• IV. Percent Error- measures accuracy
• A. Absolute Error (Ea)
• B. Relative error (ER) is calculated by taking
  the observed value (O) minus the actual value (A)
  (this is absolute error (Ea)) and dividing by
  the actual value (A) then multiplying by 100.
• C. Relative error is a measure of accuracy

V. Deviation measures precision A. Absolute
Deviation (Da) B. Relative Deviation (DR) is
calculated by taking average of the absolute
deviations and dividing by the mean (M) then
multiplying by 100. C. Relative deviation is a
measure of precision.
20
Scalars and Vectors

• Scalar quantities have magnitude only No
  Direction- can be expressed by single numbers
  with appropriate units Ex. Energy Temperature
• Vector quantities require magnitude and direction
  for their complete description. Trigonometric
  rules of vector addition must be followed to
  solve vector problems. The resultant may be
  calculated mathematically or measured graphically
  with a carefully constructed diagram.

21
Problem Solving

• Use dimensional analysis (factor labeling) to
  solve word problems
• Conversion factors should be used to cancel the
  units you dont want and leave behind the units
  you do want
• Always list the information you do know then read
  carefully to find out what you need to calculate.
  Set up the problem to solve for what you want to
  know. Check your answer to see if it is
  reasonable and in the correct units.
• Practice - Practice - Practice
• You must have this skill!

22
Pythagorean Theorem

• http//127.0.0.126300/Principles_of_Physics/01_Me
  asurement20and20Mathematics/17/sp.html

23
Trigonometric Funtions 

• http//127.0.0.126300/Principles_of_Physics/01_Me
  asurement20and20Mathematics/18/sp.html

24
Sample problem trigonometry

• http//127.0.0.126300/Principles_of_Physics/01_Me
  asurement20and20Mathematics/20/sp.html

25
Your Turn!

• http//127.0.0.126300/Principles_of_Physics/01_Me
  asurement20and20Mathematics/21/sp.html

26
Problem Solving cont

• Graphing
• Label each axis with the variable and unit and
  give the graph a title
• Independent variable goes on the X axis Dependent
  variable on the Y axis
• Plot data points and connect with a best fit line
  (not dot to dot)
• Use the finished graph to establish relationships
  (directly proportional, inverse, logarithmic)
  between the variables

27
Credits

• Text Principles of Physics Kinetic Books
• Microsoft Publishing Gallary
• Microsoft Equation Editor