Transcript Physical Science: Ch 1 Notes - Riverside Community School District

Physical Science: Ch 1 Notes
A. Scientific method – a plan for gathering, organizing, and communicating
information.
The goal of any scientific method is to solve a problem or to
better understand an observed event.
Proper materials and variables are required to experiment with the Scientific
Method
Independent variable – this variable is purposefully changed and this
causes change in another variable
Dependent variable – this changes in response to the change in other
variables
Constant – a variable that does not change during the experiment
Control – the standard to which experimental results can be compared
Physical Science: Ch 1 Notes
B. Standards of Measurement
Standard - exact quantity that people agree to use for comparison
Measurements must have a number and a unit!!!!!
SI (International System of Units)- an improved version of the metric
system used and understood by scientists worldwide
SI system is based on multiples of 10 and uses prefixes to indicate a
specific multiple
Length – the straight-line distance between two points (standard unit is meter)
Volume - the amount of space taken up by an object (Liter is standard
unit)
Mass – the quantity of matter in an object or sample (kilogram is
standard)
Time is the interval between two events (seconds is standard)
Physical Science: Ch 1 Notes
C. Measuring Temperature
Thermometer – an instrument that measures temperature, or how hot
an object is
Three different scales can be used to report temperature: Fahrenheit,
Celsius, and Kelvin
Absolute Zero - the temperature where all particle motion stops
While this cannot be achieved in the lab, scientists consider 0 K to be
absolute zero
Fahrenheit (°F)
Celsius (°C)
Kelvin (K)
Water Boils
212
100
373
Human Body
98.6
37
310
Average Room
68
20
293
Water Freezes
32
0
273
Physical Science: Ch 1 Notes
D. Scientific Theory vs. Law
Scientific theory - a well-tested explanation for a set of observations or
experimental results
Theories are never proven but they become stronger if the facts
continue to support them
Example: The kinetic theory of matter says that all particles are in
constant motion
Scientific law - a statement that summarizes a pattern found in nature
Laws do not attempt to explain patterns – the explanation is provided by
a theory
Example: The Law of Gravity is constantly proven but scientists cannot
agree on a theory that explains how it works!
Physical Science: Ch 1 Notes
E. Organizing Data
Scientists organize data by using data tables and graphs – this makes it
easier to find trends and patterns
Line graph – useful for showing changes that occur in related variables.
The independent variable is plotted on the x-axis (horizontal)
The dependent variable is plotted on the y-axis (vertical)
Slope – the ratio of a vertical change to the corresponding
horizontal change
Slope = rise/run Slope = y2-y1/x2-x1
Direction proportion – a relationship in which the ratio of the two
variables is constant, so the graph is a straight line
Bar graph – used to compare a set of measurements, amounts, or
changes
Physical Science: Ch 1 Notes
F. Density - the ratio of an object’s mass to its volume D = mass/volume
The density of pure water is 1.00 g/cm3 or 1.00 g/mL
(1 mL = 1 cm3)
Each metal on the Periodic Table of Elements has a specific density value –
these values can be found in chemistry books and on the Internet
The displacement of water method allows us to find the volume (and then
density) of irregular objects
Step 1: Measure a volume of water in a graduated cylinder
Step 2: Submerge the object in water
Step 3: Measure the new water level in the graduated cylinder
Step 4: The difference in water volumes is the volume of the irregular object
Substances that have a density of less than 1.00 g/mL will float on water