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scientific system of units

The SI system, which stands for the international system, derived from the French (system international).


What are the base units in the SI system?

second (s) = time
meter (m) = distance
kilogram (kg) = mass
Kelvin (K) = temperature
mole (mol) = mass


What are derived units?

Units that are created as derivations from the base units. There are many different derived units, but several common ones are the liter (volume), and degrees Celsius (temperature).


relationship between degress Celsius and degrees Kelvin

K - 273 = C


metric conversion using the t method

1. make a t
2. put whatever you want converted in the top left (4 m)
3. put the units of whatever is in the top left of the box, in the bottom left (m)
4. put the units of what you want to find in the top right of the box (mm)
5. add a conversion factor that converts the two units you're working with; if you're converting between two metric units, that factor consists of a 1 before the thing with the metric prefix, and whatever the prefix means in front of the other unit.
6. Multiply it together; numbers as usual, and units cancel each other out, leaving whatever units are left.

*Note: When using this method in the metric system, convert from what you have to the base, then from the base to another prefix.


metric prefixes

mega (M) 10^6 (1 million)
kilo (k) 10^3 (1 thousand)
centi (c) 10^-2 (1 hundredth)
milli (m) 10^-3 (1 thousandth)
micro (µ) 10^-6 (1 millionth)
nano (n) 10^-9 (1 billionth)



how close your measured value is to the actual value



how consist your measured values are with each other; precision implies accuracy, but it does not guarantee it


calculating percent error; percent error = ?

(error in measured value/actual value of thing measured) * 100


telling the number of significant figures that a value has

1. Any nonzero digit is significant.
2. Any zeros that are between nonzero digits are also significant.
3. All zeros to the right of the last nonzero number are not significant, unless you see a decimal written out.
4. Zeros to the left of the last nonzero number are not significant.
5. Counting numbers and other distinct values have infinite sig figs; for example, 1 Coke is one Coke precisely.


rules for operating on sig figs

addition and subtraction: round your answer to the least precise decimal place of the value you're doing a calculation with
multiplication and division: round your answer so that it has the same number of sig figs as the least precise value


rules for a good line graph

1. give it a title; either (a) the effect of ___ on ___, or (b) the dependence of ___ on __