1. 3.1A Measurements and Their Uncertainty
Chapter 3
3.1A Measurements and Their Uncertainty

2. Measurement… Number Unit Fundamental to the experimental sciences
Units in science = International System of Measurements (SI)

3. Scientific Notation
Scientific notation is an easier way to express a very small or very large number.

4. The coefficient (first number) must always be less than ten.
The exponent depends on how many decimal places you must move.

5. Scientific Notation Continued
For example, 26,000,000,000 would be written as 2.6 X 1010.
Any number smaller than 1 would get a negative exponent (ex = 3.52 X 10-9).

6. Need More Help??
Pg. R56 of Appendix C

8. Rounding Five or more, raise the score… Four or less, let it rest…
Round the following to TWO decimals:
X 10-2

9. Accuracy
How close a measurement comes to the TRUE value.

10. Precision
How close measurements are to one another.

12. Percent Error Accepted Value: “Correct Value”
Experimental Value: Value you measured in your experiment (you weighed it)
Absolute Value: Makes the value positive

13. Percent Error Calculation
Error = experimental value – accepted value
% Error = (|Error|/Accepted Value) X 100
Taking the absolute value of the error (top) always gives you a positive answer.

14. Example
If an object that weighs 54 grams is weighed to be 53.2 grams, what is the percent error?
Answer: 1.48 %
If a car is thought to be going 32 mph but is actually clocked at 35 mph, what is the percent error?
Answer: 8.57 %

15. “zero out” the scale to ensure that your weights are accurate.
Zeroing A Scale
“zero out” the scale to ensure that your weights are accurate.