1. Unit 0: Orientation to Class The Structure of Physics
McCaskie, Room 210
2017 – 2018

2. What is Physics?!? PHYSICS:
The branch of science that involves the study of the Physical world
What is “The Physical World?”

3. Physics deals with 3 things
Energy
Forces
Motion
KNOW THIS!

4. First Thing is first – the scientific method
Make an observation
Research/gather information
Form a hypothesis
Test the hypothesis (i.e. experiment)
Analyze data
Draw conclusions
Peer review

5. Which is the best way to approach a hypothesis?
What is a hypothesis?
Hypothesis
Which is the best way to approach a hypothesis?
Possible explanation based on what is already known
Based on observations 
Leads to a model 
Dictates experimentation
Objective – not influenced by personal feelings
Subjective – influenced by personal feelings, tastes or opinions

6. What is a model?
A representation of an idea, event, structure, or object that helps people understand it better

7. Modern computer models

8. Scientific Theory or Scientific Law
Explanation of things or events based on knowledge gained from observations or investigations
“You know what? I think…”
Statement about what happens in nature and seems to be true all the time
Based on countless “proven” theories
For Instance, Gravity

9. Science has limitations
It cannot explain everything!
It is a procedure that either “proves or disproves” a guess
Must be tested
What is the problem with that?
It is rooted in objectivity

10. The fun part…
GET READY…
IT’S COMING…

11. WHY the H*** do we need math in physics?!
Equations show relationships between measurements
Theories  experiments  numerical results  analysis  models that can be used to investigate similar observations

12. International system of Units (SI) Base Units KNOW THESE!!!
Length = meter (m)
Mass = kilogram (KG)
Time = second (s)
Temperature = Kelvin (K)
Amount of a substance = mole (mol)
Electric current = ampere (A)
Luminous intensity = candela (cd)

13. SI Unit conversions

14. Practice… How many centigrams are in 100 grams?
How many megagrams are in 4 milligrams?
How many nanograms are in a hectogram?
How many grams are in micrograms?

15. Dimensional analysis

16. Dimensional analysis
A relationship between all units and dimensional analysis is a way to surf between those units
For instance, how many cars are in a week? …yes you can!
A method of treating units as algebraic quantities that can be cancelled in order to predetermine if your physics equations are set up properly

17. Dimensional analysis practice
How many feet tall is a peak that is 8000 meters tall?
If an apartment has an area of 880 square feet, how many meters is that?
A posted speed limit sign state the speed limit is 55 miles per hour. How fast is that in meters per second? In kilometers per hour?

18. Break time?

19. Significant figures Definition – valid digits in a measurement
Measurement is inherently flawed, based on user error, and imprecise tools
Therefore, number of significant figures is determined by how precise the measurement is
is your pen 138 mm? mm?
mm? mm?

21. Rules for significant figures
Nonzero digits are always significant
37 = 2 sig figs
Any zero between 2 nonzero digits are significant
407 = 3 sig figs
Final zeros to the right of a decimal point are significant
37.0 = 3 sig figs
Zeros to the left of a decimal point/Space holding zeros are NOT significant
4500 = 45 X 102 = 2 sig figs
YEP! KNOW THIS TOO!!!!

22. Measurement

23. Measurement = comparison between an unknown quantity and a standard
Mass of a shopping cart
Blood pressure
Height
weight
Gram (g)
Range between 110/60 – 130/90 mmHg
Meters (m)
Gram (g)/ kilogram (kg)

24. Precise vs. accurate Precision Accuracy
How well the measurements “agree” with the real value
How close are all measurements to each other
Degree of exactness
“how close to the bullseye?”

25. Graphing Data

26. First Identify variables
Independent variable – the factor that is being manipulated
Ex.: masses of different object hanging from different springs
Dependent variable – the factor that depends on the independent Variable
Ex.: springs stretching in response to masses

27. Create a graph X- and y- axes
Shows the relationship between independent and dependent variables

28. Example of constructing a graph
Mass attached to spring
Length of spring
13.7 5
14.1 10
14.5 15
14.9 20
15.3 25
15.7 30
16.0 35
16.4

29. Practice time

30. Types of graphical relationships
Linear
Nonlinear
Dependent variable varies linearly with independent variable
Y = mx + B
Dependent variable varies in a non- linear fashion with independent variable
Quadratic functions
Inverse relationships

31. Nonlinear relationships
Quadratic Relationship
Inverse relationship