Introduction to Physics
Study of the physical world. Science of energy.
The metric system is based on prefixes that indicate a power of 10
with base units.
Metric Prefixes commonly used in
The International System of units gives a standard unit for each
type of measurement.
SI Units commonly used in physics
|Amount of substance
To work dimensional analysis problems:
- Write your known down on the left side
- Write down “=__________ [desired unit]” at the right
- Identify equalities that will get you from the known
information to the desired unit. If there is no equality
that involves both the known and unknown, you’ll have to
find more than one to more than one step.
- Arrange the equalities into a fractional form so that
the known unit will cancel out and the desired unit will be
- Multiply across the top of the expression and divide
numbers on the bottom.
Measurements and uncertainty:
Measurements must be taken accurately. Always write down one more
decimal place than the instrument tells for certain—a “0” if it’s
“one the line” and a “5” if it’s “between the lines.”
The significant figure rules are to allow people to read data or
calculations and know with what precision the data was taken. The
significant rules can be summarized in two rules: (1) If a decimal
point is not present, count digits starting with the first the first
non-zero number and ending with the last non-zero number; (2) If a
decimal point is present anywhere in the number, start counting with
the first non-zero number and continue until the end of the number.
There are many paths to follow when undertaking “science”—there is
no one scientific method. Science involves observing, posing
questions, forming possible explanations (hypothesis),
experimenting, processing/analyzing data, looking for trends, more
formation of possible explanations or question posing. Scientific
processes form theories (which attempt to explain observed behavior)
and laws (which describe or predict behavior, and are usually
mathematical). A theory cannot become a law—one explains why and
one describes what. A hypothesis is a proposed explanation for why
something will occur (that may become a theory with enough
evidence), while a prediction is simply a guess at what will
happen—it does not attempt to say “why” it will happen.