1. Section 2 Measurement: Errors, Accuracy, and Precision
WDYS? (p22) 1. 2. 3.
WDYT?
3m vs. 10m = yes OR no
3m vs. 3.01m = yes OR no
Investigate – you will measure a given distance by various techniques

2. 1-2 NOTES “Errors in Measurement”
In 1-2 INVESTIGATE, you measured distance with:
1. Stride
2. Meter stick
3. Tape measure
What did we learn???
There are NO exact measurements
With each successive (REPEATED) method, the error range became less

3. A. Random Errors (human)
1-2 NOTES “Errors in Measurement”
A. Random Errors (human)
Random Errors  errors that cannot be corrected by calculating
The uncertainty can never be completely eliminated, no matter how good the instrument or scientist
Uncertainty= [ high measurement – low measurement ]
B. Systemic Errors (tool)
Systemic Errors  an error produced by using the wrong tool or using the tool incorrectly
EXAMPLE You write 4m instead of 4yds

4. Example: Ava measures the mass of an object 10.2 kg 11.7 kg 12.3 kg
What is the value of the mass? (include uncertainty)

5. C. Accuracy and Precision
Accuracy  how close a series of measurements are to an accepted value
EXAMPLE NEAR the target area
Precision  the frequency with which a measurement produces the same results
EXAMPLE GROUPED together

6. D. Significant Figures ALL non-zeros are significant.
How many do we “keep”?
Rules for identifying significant figures:
ALL non-zeros are significant.
All “Sandwiched” zeros are significant
Leading zeros are never significant
Trailing zeros are only significant if there is a decimal present

7. D. Significant Figures
Where do our numbers come from?
2. Measurement:
Get as good as the instrument can take you, estimate one more!
Example:

8. D. Significant Figures (cont.)
MATH AND SIGNIFICANT FIGURES
Adding and subtracting—keep the LEAST number of significant figures AFTER the decimal
Multiplying and divining—keep the LEAST number of significant figures.