1. Science, Measurements, Uncertainty and Error
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Science, Measurement, Uncertainty and Error

2. Conversion Factor- Conversion of Units
A conversion factor is a ratio between two units:
The conversion factor can be written with either value on top, just set it up so that units cancel out!

3. Example 27.777...m/s How fast is 100 km/h in m/s? Write what you have…
multiply by conversion factor(s)…
m/s
do the math…
multiply the tops,
multiply the bottoms,
then divide these 2 #’s

4. Example How fast is 50mph in m/s? Write what you have…
multiply by conversion factor(s)…
do the math…
multiply the tops,
multiply the bottoms,
then divide these 2 #’s
m/s

5. Precision http://smedia.vermotion.com/media/12933/resources/60000.JPG

6. Accuracy http://smedia.vermotion.com/media/12933/resources/60000.JPG

7. Dartboard analogy
Imagine a person throwing darts, trying to hit the bulls-eye.

8. Scientific Data
Scientists always want the most precise and accurate experimental data.
The precision and accuracy are limited by the instrumentation and data gathering techniques.

9. Dealing with Errors HOW? Identify the errors and their magnitude.
Try to reduce the magnitude of the error.
HOW?
Better instruments
Better experimental design
Collect a lot of data

10. Counting Sig Fig’s – 4 Rules:
Nonzero digits are always significant
All final zeros after the decimal point are significant
Zeros between two other significant digits are always significant
Zeros used solely as placeholders are not significant

11. Counting Sig Fig’s – Sci. Notation
Use Scientific Notation…
Determine how many digits are important when writing the number in scientific notation.

12. How many significant figures?
1,460
726.01
1.47
1,200
21.76
720
421.03
4.801
1,200,000.0
.002
0.103
120
1,000.1
4.60

13. How do you round? Rounding is different, depending on whether you are
adding or subtracting OR
multiplying or dividing

14. Multiplying/Dividing
Adding/Subtracting
Add/Subtract first
Round according to the fewest number of Digits After the Decimal
Multiplying/Dividing
Multiply/Divide first
Round according to the fewest number of Significant Figures

15. Examples:
286.9
2.251
507.8

16. Examples:
12,000 92
380