Physics

1
Physics

• An introduction

2
The Laws of Nature

• Physics was originally called the Philosophiae
  Naturalis or the Natural Philosophy
• Physics is the study of the fundamental laws of
  nature (the laws that underlie all physical
  phenomena).
• So, why is physics important?
• It relates to everything in the universe and
  remember you are in the universe too!

3
Scientific Method

• Recognize a problem
• Make an educated guess - a Hypothesis about the
  answer
• Predict the consequences of the hypothesis
• Perform experiments to test predictions
• Formulate the simplest general rule that
  organizes the hypothesis, prediction, and
  experimental outcome

4
Theory

• The word theory, as used in everyday speech is
  different than the word theory, as used in
  scientific dialogue.
• In everyday language, theory is like the
  scientific hypothesis
• A scientific theory is a synthesis of a large
  body of information that encompasses well-tested
  and verified hypotheses about certain aspects of
  the natural world.

5
Units of length, mass, and time

• Standard units in physics are refered to SI
  (système international) units. For length, mass,
  and time they are
• The meter, m
• The kilogram, kg
• The second, s
• These are also, in physics, called the MKS units

6
Prefixes, Powers, and Abbreviations
7
Powers of Ten

• http//micro.magnet.fsu.edu/primer/java/scienceopt
  icsu/powersof10/index.html

8
Significant Figures

• Observed values of experimental quantities have
  inherent uncertainties
• These uncertainties should always be kept in mind
  when performing calculations with those values

9
Example

• But how can your speed be so accurate?It cant,
  you must apply sig fig rules. The correct answer
  is 2.5 cm/s. Heres why

10
Sig Fig Rules

• The number of sig figs after multiplication or
  division is equal to the number of sig figs in
  the least accurately known quantity
• The number of decimals places after addition or
  subtraction is equal to the smallest number of
  decimal places in any of the individual terms

11
Sig Fig Counting
12
Sig Fig Counting

• 1 sig fig
• 321,000,000 3 sig figs
• 21,956 5 sig figs

13
Scientific Notation

• Only include the sig figs in scientific notation

14
Round-off Error

• Wait until the end of a calculation to round and
  sig fig (you see I made sig fig a verb).

15
Converting Units

• Dimensional analysis see board and book for
  examples
• Usually we will remain within the metric system
  but occasionally we will go from American
  (Imperial) to metric
• Converting time is also an important one

16
Math

• graphing p 21 22 example
• Coordinate Systems
• Algebra
• Trig

17
Error

• Percent Error

18
Words

• Accuracy If your measurements are close to the
  accepted value
• Quality of Precision How close your measurements
  are to each other
• Level of Precision How specific your measuring
  device is

19
Order of Magnitude

• Determining the power of ten that is closest to
  the actual numerical value of the quantity before
  actually calculating the quantity.
• Order of magnitude estimate for height of
• Sled hill at West Park
• Mountain in Colorado
• a) 1 m b) 10 m c) 100 m d) 1000 m

20
Homework and Reading

• Read Ch 1
• pp 3 - 26

• HW due on test day
• p 15 1 5, p 20 1 4, p 25 1 5, p 28 15
  20