1. Chapter 1
The Science of Physics

2. 1-1: What is Physics?
We are surrounded by the principles of physics in our everyday lives.
Any problem or question that deals with temperature, size, motion, position, shape or color involves physics.

3. The Areas of Physics:

4. Classical Mechanics
motion of macroscopic objects at low speeds (v << c)
Examine motion & its causes. Ex: falling objects, weight, friction, etc.

5. Thermodynamics
deals with heat, work, temperature, and the statistical behaviour of a large number of particles

6. Vibrations & Waves
Deals with specific types of repetitive motion.
Ex: springs, pendulums, sound…

7. Optics
Deals with light and its properties.
Ex: mirrors, lenses, color…

8. Electromagnetism
theory of electricity, magnetism and electromagnetic fields
Ex: electric charge, circuits, permanent magnets

9. Relativity
motion of objects at any speed, including very high speeds
Ex: particle collisions, nuclear energy

10. Quantum mechanics
theory dealing with behaviour of particles at atomic levels

11. The Science of Physics Thermodynamics: Electromagnetism:
Heat and temperature
Efficient engines, coolants
Electromagnetism:
Battery, starter, headlights
Optics:
Headlights,
rear-view
mirrors
Vibrations and
Mechanical waves:
shocks, radio speakers
sound insulation
Mechanics:
Spinning motion of the wheels,
tires that provide enough
friction for traction – all motions

12. Scientific Method
Make observations & collect data that lead to a question.
Formulate and objectively test hypotheses by experiment.
Interpret results, and revise hypothesis if necessary.
State conclusions in a form that can be evaluated by others.

13. Models in physics
A model is a replica or description designed to show the structure or workings of an object, system or concept.
Simplify
Help build hypotheses
Guide experimental design
Make testable predictions

14. 1-2: Measurement

15. Physical Quantity vs. Units
Physical quantity- any characteristics of objects that can be measured. Ex: length, mass, temperature
Units of measure- basic standards of measurement Ex: length can be measured in miles or meters

16. SI Standards UNIT Original standard Current standard Meter (length)
1/10,000,000 distance from equator to North Pole
Distance traveled by light in a vacuum in 3.3 x 10-9 s
Kilogram (mass)
Mass of cubic meters of water
Mass of a specific platinum-iridium alloy cylinder
Second (time)
(1/60)(1/60)(1/24)= average solar days
9,192,631,700 times the period of a radio wave from cesium-133

17. Other units are DERIVED units, that is, they are calculated from measurements in the base units.
Examples are velocity (m/s), acceleration (m/s2), or density (g/cm3).

18. Prefixes Symbolize powers of 10
Used to accommodate very large/small quantities
Commonly used prefixes on table 1-3, pg. 12

19. Conversions
Conversion factor- ratio used to convert from one unit or prefix to another
Used in the factor-label method to express answers in the desired units.
Example: 1 mile = 1.61 km

20. Example: Convert 10.0 miles into kilometers
Conversion factor: 1 mile = 1.61 km Set up the conversion so that miles cancel when multiplied # km = 10.0 mi x 1.61 km = mile

21. Sample Problem
“Oh man,” a bleary-eyed student once noted, “That lecture on classroom policies must have gone on for a microcentury.” How many minutes are there in a microcentury?

22. Solution
Micro = 10-6

23. Accuracy & Precision
Accuracy- how close a measurement comes to accepted value
Precision- degree of exactness, small variation between repeated measurements

24. Measurement / Significant figures
Uncertainty in measurement depends on the quality of the apparatus, skill of the experimenter and number of measurements performed
Sig figs keep track of imprecision
Sig figs include all measured digits plus one estimated digit
, see rules for sig figs on pg. 17
See rules for calculating & rounding pg 18 & 19

25. Sig Figs 10.3 : read as much as you can and estimate one digit 11 12

26. The rules for significant digits
1. All whole number digits are significant.
Ex. 1, 2, 3, 4, 5, 6, 7, 8, 9
245, significant digits
14,328 ________________
96 ________________

27. The rules for significant digits
2. Rules for Zeros
a. Zeros between other nonzero digits are significant.
Example:
significant digits
_____________
_____________

28. The rules for significant digits
b. Zeros in front of nonzero digits are not significant
Example
significant digits
______________
____________

29. The rules for significant digits
c. Zeros that are at the end of a number and also to the right of the decimal are significant.
Example
significant digits
______________
______________

30. The rules for significant digits
d. Zeros at the end of a number without a decimal are not significant.
Example
significant digit
46000 ______________
______________

31. The rules for significant digits in calculations
1. Addition or subtraction - The final answer should have the same number of digits to the right of the decimal as the measurement with the smallest number of digits to the right of the decimal.

32. Example
= (15.03)
= _________
– 2.44 – 1.6 = ________

33. The rules for significant digits in calculations
2. Multiplication or division – the final answer has the same number of significant figures as the measurement having the smallest number of significant figures.

34. Example
4.0 x 2.11 x = 29
(actual answer is )
4.01 x 4.1 / = _______
/ / 2 = _______

35. Scientific Notation Scientific Notation- in the form of A x 10 n
1< A< 10 and n = power of 10
A contains only sig figs of original number/measurement

36. 1-3: Language of Physics
Tables, Graphs, & Equations

37. Tables, graphs & equations make data easier to understand
Equations used to describe relationship between physical quantities
Appendix B pg lists variables, symbols & constants used

38. Dimensional Analysis Dimensional analysis used to:
- check a specific formula
- give hints as to the correct form the equations must take
Dimensional analysis does not give any information on the magnitude of the constants of proportionality

39. Orders-of-Magnitude Refers to the nearest power of 10
Useful to compute an approximate answer
Results can be used to decide whether a more precise calculation is necessary
Assumptions are usually needed