# Fundamental quantities of science ```Fundamental quantities of science - SI units
Length - meter (m)
We'll usually use 'x', 'y', or 'l' to represent distance or
length
Mass - kilogram (kg)
We'll usually use 'm' to represent mass
Time - second (s)
We'll usually use 't' to represent time
The Building Blocks of Matter
Molecules  Atoms
Atoms  Particles (Protons, Neutrons, Electrons)
Particles  Quarks (up, down, strange, charm, bottom, top)
Quarks  Strings (?)
Dimensional Analysis
The process of using units (dimensions) to determine
relationships between variables. Dimensional analysis
cannot determine if there is a &quot;constant of proportionality&quot;.
Significant Figures
Addition/Subtraction: The number of decimal places in the
result should equal the smallest number of decimal places
of any term in the sum/difference.
4.56 + 2.045 = 6.61 (6.605)
Multiplication/Division: The number of significant figures
in the final result is the same as the number of significant
figures in the least accurate of the values being combined,
where least accurate means having the lowest number of
significant figures.
3.1 x 6.51 x 0.773 = 15 (15.599913)
Conversions
Conversion factors are located in the front cover of your
textbook.
Convert 1200m into ft…
1 m = 3.281 ft
1200 m = 1200 x 3.281 ft
1200 m = 3937 ft
Convert 12 cm2 into m2
100 cm = 1 m
1 cm = 1/100 m
12 cm2 = (1/100)2 m2
12 cm2 = 12 (1/100)2 m2
12 cm2 = 0.0012 m2
Convert 4.50 x 103 kg/m3 to g/cm3
Coordinate System
We use the Cartesian coordinate system a.k.a. the
rectangular coordinate system. Points are labeled (x,y).
Sometimes it is more useful to locate a point by its plane
polar coordinates (r, ). We use trigonometry to convert
from Cartesian (rectangular) to polar coordinates.
y = r sin 
x = r cos 
r2 = x2 + y2
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