Physics:
Study of the physical world. Science of energy.
Metric System
The metric system is based on prefixes that indicate a power of 10 with base units.
Metric Prefixes commonly used in physics |
Prefix |
Symbol |
Multiple |
Kilo |
k |
1000 |
Deci |
d |
0.1 |
Centi |
c |
0.01 |
Milli |
m |
0.001 |
Micro |
m |
0.000001 |
Nano |
n |
0.000000001 |
SI system
The International System of units gives a standard unit for each type of measurement.
SI Units commonly used in physics |
Measurement |
Unit |
Symbol |
Mass |
Kilogram |
kg |
Volume |
Liter |
L |
Temperature |
Kelvin |
K |
Length |
Meters |
m |
Time |
Seconds |
s |
Amount of substance |
Mole |
Mol |
Energy |
Joule |
J |
Charge |
Coulomb |
C |
Dimensional analysis:
To work dimensional analysis problems:
- Write your known down on the left side
- Write down “=__________ [desired unit]” at the right side
- 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 left.
- 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.”
Significant figures:
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.
Scientific process:
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.