Scientific method
a method of investigation involving observation and theory to test scientific hypotheses
Robert Boyle
pioneered the use of the scientific method; "first true scientist"
Steps in the scientific method
Observations
Hypothesis
Testing (experimentation)
Statement of a theory Steps 1-3 are a repeating cycle.
Observation
noticing a change or occurrence; collecting data
Statement of a hypothesis
making an educated guess to explain why the observation occurred; stated in the format, "if _____, then ______"
Experimentation/testing
create an experiment to test your hypothesis (either prove or disprove); results tell you if the hypothesis needs adjusting and can restart the cycle of observation, hypothesis, testing.
Statement of a theory
after collecting enough data from a series of explanations, a coherent set of explanations (theory) may be deduced
Law
general statement of fact; a "what," not a why
Theory
explains the "why"; supported by coherent explanations
Scientific notation
method of representing numbers in exponential form
Mantissa
first portion of a value expressed in scientific notation; number between 1 and 10; "decimal portion"
Ordinate
second portion of a value expressed in scientific notation; base 10 raised to some power; "exponential portion"
Linear relationship
y = Kx
Inverse relationship
y = K/x
Exponential relationship
y = Kx^n
SI system
International System of Units; modern metric system
Base unit of length
metre (m)
Base unit of mass
kilogram (kg)
Base unit of time
seconds (s)
Base unit of electric current
ampere (A)
Base unit of temperature
kelvin (K)
Base unit of luminous intensity
candela (cd)
Base unit for amount of substance
mole (mol)
Base unit for area
square metre (m^2)
Base unit of volume
litre (L)
Accuracy
the agreement of a particular value with its true value
Precision
exactness of a measurement
Systematic error
a group of errors that consistently appears in the same direction
Random error
a group of errors that appear in different directions
Range uncertainty
an acceptable range of values within which the true value of a measurement falls; commonly presented using plus or minus notation
Absolute uncertainty
exactly how much higher or lower a measured value is than an accepted value
Percentage error
(measured value - accepted value) / accepted value x 100%
Significant figures
all of the certain figures plus the first uncertain (estimated) figure
Dimensional analysis
a method that allows you to easily solve problems by converting one unit to another through use of conversion factors
Conversion factor
fraction or factor written so that the denominator and numerator are equivalent values with different units
Defined values
accepted values that do not affect the number of sig figs in an answer
giga
G; 10^9
mega
M; 10^6
kilo
k; 10^3
hecto
h; 10^2
deca
da; 10^1
deci
d; 10^-1
centi
c; 10^-2
milli
m; 10^-3
micro
μ; 10^-6
nano
n; 10^-9
Derived unit
unit composed of more than one unit; example: km/h