Science Measurements Uncertainty and Error Science Measurement Uncertainty

Conversion Factor- Conversion of Units p A conversion factor is a ratio between two

Example p How fast is 100 km/h in m/s? Write what you have… multiply

Example p How fast is 50 mph in m/s? Write what you have… multiply

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

Scientific Data Scientists always want the most precise and accurate experimental data. The precision

Dealing with Errors p Identify the errors and their magnitude. p Try to reduce

Counting Sig Fig’s – 4 Rules: 1. 2. 3. 4. Nonzero digits are always

Counting Sig Fig’s – Sci. Notation Use Scientific Notation… p Determine how many digits

How many significant figures? 1, 460 726. 01 21. 76 720 421. 03 4.

How do you round? p Rounding is different, depending on whether you are n

Adding/Subtracting Add/Subtract first p Round according to the fewest number of Digits After the

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

Conversion Factor- Conversion of Units p 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!

Example p How fast is 100 km/h in m/s? Write what you have… multiply by conversion factor(s)… 27. 777. . . m/s do the math… multiply the tops, multiply the bottoms, then divide these 2 #’s

Example p How fast is 50 mph 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 22. 3472 m/s

http: //smedia. vermotion. com/media/12933/resources/60000. JPG http: //www. gototem. com/Webgifs/Clip. Art/Sports/Darts. GIF

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

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.

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

Counting Sig Fig’s – 4 Rules: 1. 2. 3. 4. 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

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

How many significant figures? 1, 460 726. 01 21. 76 720 421. 03 4. 801 . 002 0. 103 1, 000. 1 0. 000827 1. 47 1, 200, 000. 0 120 4. 60

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

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

Examples: 286. 9 2. 251 507. 8

Examples: 12, 000 92 380