1. Measurement and Conversions
Remember: Have fun!!!

3. Importance of Measurement
Qualitative Measurements
Descriptive nonnumeric form
“Qualities” or physical properties
Quantitative Measurements
Definite form, usually as numbers
“Quantities” or How much?/How many?

4. Accuracy vs Precision /Reproducibility
Refers to the closeness of measurements to the correct or true value
Reproducibility (Precision)
Refers to the closeness of several measurements to the same value, not necessarily the true value
Precision is a measure of exactness of a measurement. The more significant figures, the higher the precision, ex: 4.02, and (3 .0 is more precise than just 3)

5. Accuracy Vs. Reproducibility
Scientists aim for both accuracy and reproducibility in their measurements

6. Significant Figures in Measurement
High accuracy, low reproducibility
Low accuracy, high Reproducibility
In Science, measurement should be Accurate and Reproducible
Accuracy = close to the actual/true value or the target
Reproducibility refers to how close a group of measurements are to each other .

7. Significant Figures in Measurement
The valid digits in a measurement are called significant digits.  Measurements are made with measuring tools that have a calibrated (standardized) scale.
The last digit given for any measurement is the uncertain or estimated digit.  It is uncertain because it is estimated. 

8. Significant Figures

9. Why is this important?
Significant figures were created to help scientists determine how they should round off their answers.
Precision is a measure of exactness of a measurement. The more significant figures, the higher the precision, ex: 4.02, and
Precise measurements of time are also important in sports. Just ask Phelps and Cavic (50.58 to 50.59)
Phelps-video

10. Practice
Each of five students used the same ruler to measure the length of the same pencil. These data resulted: cm, cm, cm, cm, cm. The actual length of the pencil was cm. Describe whether accuracy, reproducibility and precision are each good or poor for these measurements.

11. Measuring to a significant figure (precision)
Contain all digits that are known precisely plus one last digit that is estimated
How long is the nail?

12. Significant figures in a measurement
Which digits in a measurement are significant?
Every nonzero digit
Certain zeros are significant
See chart

14. How many significant figures are in each or the following measurements?
0.123 cm
9.80
22.80 m

15. Significant Figures in Measuement
Measurements are always measured by estimating between the smallest graduation given.
The top ruler measures with more precision
There is uncertainty in the last digit of a scientific measurement only

16. Measure each object to a correct significant figure with different rulers

17. Measure the following to a significant figure
Using the ruler below, record the position of the arrow to the nearest mL. Show the correct number of significant figures.

18. Scientific Notation
A number written as a product of two numbers: a coefficient and a power of 10
Used for very large or very small numbers
3.6 x 104
Coefficient Power of 10

19. Scientific Notation 3.6 x 104 3.6 x 10 x 10 x 10 x 10 = 36000
Decimal moves Exponent is 4
Places to the left

20. Scientific Notation 8.1 x 10-3 8.1 = 0.0081 10 x 10 x10=
10 x 10 x10
= 8.1 x 10-3
Decimal moves Exponent is -3
places to the right

21. SI units of Measurement
The International System of Units (SI)
Standard of measurement used in science
Revised version of the metric system
Units based on 10
Seven base units
Derived units, such as volume, density etc.

22. Base units
Gram - the measure of mass, the amount of matter (size of a small paperclip)
Meter – the measure of length (one large step)
Liter – the measure for volume, how much space something takes up (about 4 cups)
Newtons- the measure of weight (force of gravity on something)
Seconds – the measure of time

23. Base Units Degrees Celsius or Kelvin measure Temperature
Absolute zero is degrees Celsius
or 0 degrees Kelvin
Nothing is colder than absolute zero

24. Prefixes that change the value

26. KHDBDCM King Henry Died By Drinking Chocolate Milk! Kilo (k)- 1000
Kings Hate Dragons Because Dragons Chase Maidens
Kilo (k)- 1000
Hecto (h)- 100
Deka (da)- 10
Base Unit (m,g, l) 1
Deci (d)– 0.10
Centi (c) 0.01
Milli – (m) 0.001

27. What unit would I use to measure:
The length of your desk?
The height of the ceiling?
The amount of water in a swimming pool?
The mass of a pushpin?
The mass of a person?
The amount of water in a fish tank?

28. Converting from one unit to another
Makes huge numbers make more sense
Makes extremely small numbers make more sense
Water is what the metric system is based on!!
1cmᶟ = 1ml = 1g

29. Converting from one unit to another

30. KHDBDCM Divide by 10 Multipy by 10 K H D B D C M
(arrows show the direction to move the Decimal Point)
K H D B D C M
Kilo Hecto Deka Base Unit Deci Centi Milli
(Gram, Meter, Liter)
Thousand Hundred Ten One Tenths Hundredths Thousandths
_____ _____ _____ _____ . _____ _____ _____

31. Examples (Dimensional Analysis 1)
Convert: (2 meters into centimeters)
2m=________ cm

32. Dimensional Analysis 2
Convert:
12 ml = ____________ L

33. Dimensional Analysis 3
Convert:
40 g = __________ Kg