Chapter 1 The Science of Physics
1-1 What is Physics?
 What does Physics mean?
"Physics" is from the Greek root physik (science of
nature) and Latin physica (natural science).
 It’s the scientific study of matter, energy, force,
and motion, and the way they relate to each
other.
 Studies how things work in the material universe.
http://www.youtube.com/
watch?v=AEIn3T6nDAo&f
eature=youtu.be
Video – The Big bang tv
show – “what is Physics?”
Physics explains things that are very,
very large.
Physics explains things that
are very, very small.
1-2 Measurements in Experiments
Scientific Notation
 Extremely large or small numbers are expressed in
powers of ten.
6.02 x 1023
1.6 x 10-19
Rules:
 When adding or subtracting numbers written in scientific notation exponents
must be the same. Move the decimal point to the left you add one to the
exponent, when moving decimal point to the right you subtract one from
exponent.
 When dividing 2 numbers written in scientific notation subtract exponents.
 When multiplying 2 numbers – add exponents.
Example:
4.25 x 107 + 2.25 x 108
2.68 x 108 or 26.8 x 107 are equal – same value
Scientists use the International System of Units, or SI.
Common SI base Units:
Length – meter (m)
Mass – kilogram (kg)
Time – second (s)
Electric Current - ampere (A)
Thermodynamic Temperature – kelvin (K)
Amount of a substance - mole (mol)
Derived Units – units that came from a combination
of other units
Example: Newton and speed
1 kg / m/s2
and
m/s
The Metric System
I’m ten times better
than the Standard
system of
measurement!”
 Regardless of the unit, the entire metric system
uses the same prefixes.
Some common prefixes:
•giga = G
x10+9 or billions
•mega = M
x10+6 or millions
•kilo = k
x10+3 or thousands
•centi = c
x10-2 or hundredths
•milli = m
x10-3 or thousandths
•micro = 
x10-6 or millionths
•nano = n
x10-9 or billionths
•pico = p
x10-12 or trillionths
 To convert measurements use Dimensional Analysis by
multiplying by a conversion factor: a factor equal to one.
Example: To convert 56 m to km --
56 m x 1 km = 0.056 km
1000 m
Example:
Convert 65 mph to km/hr
Conversion factor
65 mi/hr x 1.61 km/hr
1 mi /hr
= 104 km/hr
Accuracy and Precision
 Accuracy – describes how close a measurement is to the
true value of the quantity measured.
 Precision – the exactness of a measurement
 Example:
45.052 m is more precise than 45.0 m
Low Accuracy
High Precision
High Accuracy
Low Precision
High Accuracy
High Precision
Significant Figures
 Used to show the precision of a measured quantity
 Include all digits that are actually measured plus one estimated digit.
 Rules:
1) All non zero numbers are significant
738
= 3 sig figs
12345 = 5 sig figs
2) Zeros located between non-zero digits are significant
2014
= 4 sig figs
This measurement should be read
as 4.95 cm. This measurement has
3 significant figures.
3) Trailing zeros (at the end) are significant only if the
number contains a decimal point; otherwise they are
insignificant (they don’t count)
1.00 = 3 sig figs
549000. = 6 sig figs
549000 = only 3 sig figs
4) Zeros to the left of the first nonzero digit are insignificant
(they don’t count); they are only placeholders.
000.456 = 3 sig figs
0.052 = 2 sig figs
Rules for addition/subtraction problems
 The number of decimal places in the result equals the number
of decimal places in the least precise measurement
 Example:
7.939 + 6.26 + 11.1 = 25.299
 Answer =
3 sig figs
25.3 (rounded up)
Rules for multiplication/division problems
 The number of sig figs in the result equals the number in the
least precise measurement used in the calculation
 Example:
 Answer =
(27.2 x 15.63) ÷ 1.846 = 230.3011918
3 sig figs
230. (rounded down)
1-3 The Language of Physics
 Graphs and Charts
 Symbols
 In Physics there are 3 types of mathematical relationships that
are most common.
1) linear relationship (or direct relationship) expressed by the
equation y = mx + b where m is the slope and b is the y-intercept
2) Another relationship is the quadratic relationship.
The equation is y = kx2, where k is a constant.
3) The third equation is an inverse relationship,
expressed by xy = k, where k is a constant.
Trigonometry will become important when
we study vectors and parabolic motion
Way to remember trig functions:
“SOH CAH TOA”