1. St. Augustine Preparatory School
Physics Chapter 1
St. Augustine Preparatory School

2. The Scientific Method Physics follows the scientific method
Make observations and collect data
- This will allow you to formulate a question
2) Create and test a hypothesis through controlled experimentation
3) Interpret results and revise hypothesis if necessary
4) State conclusions in a form that can be evaluated by others

3. Using Models
Physics can often be very complex, so simplified models can be used
System – the interacting components considered to be necessary for the purpose of the study

4. Example: Improving the fuel efficiency of a vehicle.
Things that could potentially matter:

5. To run a legitimate and effective study, we cannot change all of these variables at once.
We must also run a “control” group that has only changed one variable.
The best physics models can make predictions in new situations

6. If we drop a roll of tape and a piece of paper at the same time, which one is going to hit the ground first? What about in a vacuum? (youtube video) What can we conclude from both of these trials?

7. SI Units
In 1960, an international committee decided on a system of standards and units, known as SI units (Systeme International d’Unites).
We have 7 base units in SI:
meter 2) kilogram 3) second 4) ampere
5) candela 6) kelvin and 7) mole

8. Random Facts: Unit Original Standard Current Standard Meter (length)
1/ th the distance from the equator to the North Pole
The distance travelled by light in a vacuum in x10-9 s
Kilogram (mass)
Mass of cubic meters of water
The mass of a specific platinum-iridium alloy cylinder
Second (time)
(1/60)(1/60)(1/24) =
average solar days
times the period of a radio wave emitted from cesium-133 atom

9. These 7 cannot explain everything though… These units have been combined to create what we call “derived units” Example: Velocity is measured in m/s (meters per second) However, force is measured in N (Newton’s)

10. Prefixes for units
You are required to know the following prefixes for units:
Pico (p): g) kilo(k): 103
Nano(n): h) mega(M): 106
Micro(μ): i) giga(G): 109
Milli(m): j) tetra(T): 1012
Centi(c): 10-2
deci(d): 10-1

11. Conversions Example: Convert 162000g to Mg
Example: Convert 1312km to meters

12. Practice conversions 10 kilograms in megagrams
kilometers in centimeters
132.5 cm in decimeters
132 millimeters to micrometers
5) 262,523 micrometers in meters
6) 2329 picograms to milligrams

13. Significant Figures
Significant figures (also called significant digits) are important as they indicate the precision of a measurement
Page 18 in your textbook has the rules for determining the amount of significant figures in a number

14. Practice 1.0303 m h) 1000 kg 2.50 kg i) 6.723 m 0.00032 s j) 4.200 J
3.0x102 mm
45 s
40 s km

15. Rules for addition and subtraction
When adding and subtracting numbers, the final answer will have the same number of decimal places as the number used in the addition/subtraction that had the least number of decimal places.
Examples: =
125 – 5.5 =

16. Rules for multiplication and division
When multiplying and dividing, the final answer must have the same number of significant figures as the number used that had the least number of significant digits.
Examples:
24.0 x 1.5 =
36.00/2.00 =

17. Practice 97.3 + 5.85 = 122.3 – 0.52 = (124.2)(2.1) = (2x102)(1.232) =
24.56 / =
2.02x x105 = =
(1.20)(2.212)(0.0035) =