LESSON 4: SI System and Percent Error
Prefixes Used with SI Units- We can put a prefix in front of the unit and change the power of it.
- tera (T): 10^12 - femto (fm): 10^-15
-giga (G): 10^9 - pico (pi): 10^-12
-Mega(M): 10^6 - nano (n) 10^-9
-kilo(k): 10^3 - micro :10^-6
- hecto(h): 10^2 - milli (m): 10^-3
- deca (da): 10^1 - centi (c): 10^-2
- the SI System uses many prefixes to represent very large or very small numbers
- Don't use scientific notation and prefixes together! It becomes very confusing
Experimental Accuracy
- In general the maximum accuracy of any measurement is one half of the smallest division of the measuring device
- A ruler with measurements of the millimeters has a maximum accuracy of positive or negative 0.5mm
Expressing Error
- Error is a fundamental part of science
- There are usually 3 reasons for error:
> physical errors in the measuring device
> "sloppy" measurements
> changing ambient conditions
Calculating Errors
- Two different possibilities: Absolute Error, Percentage Error
Absolute Error
- Measured value minus accepted value
- Absolute Error = Measured - Accepted
Percent Error
- Most common
- Percent Error = [Measured-Accepted/Accepted] x 100
posted by chemistry11 @ 9:11 AM
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