Measurements

1. Measurements

2. Which is a measurement?

3. Which is a measurement? “Numerical value and unit of measurement”

4. What is a measurement? • Process of determining a property of an object with a well-defined and agreed-upon referent or unit.

5. Accuracy vs. Precision • Accuracy • Degree of which information on the experimental values agrees with the true value of the quantity that was measured. • Precision • Exactness of the instruments and methods used to obtain a result

6. English System • Is commonly used in English-speaking countries • Also known as the British System • Used familiar objects and parts of the body were used as measuring devices.

7. English System • Inch = length of three barleycorns placed end to end. • Yard = length from the King's nose to his outstretched hand • Pound = comes from Latin “pondus” for weight. • Acre = related to the word agriculture • Gallon = Latin “galleta” and refers to a standard container about the same size as a helmet.

8. Metric System of Measurement • Based on the decimal number system • Uses prefixes in measurement • Kilo (k) = 1000 = 103 • Hecto (h) = 100 = 102 • Deka (Da) = 10 = 101 • Deci (d) = 1/10 = 10-1 • Centi (c) = 1/100 = 10-2 • Milli (m) = 1/1000 = 10-3

9. Mass vs. Weight • Mass • Measure of the amount of matter in an object • Mass is constant • Weight • Measure of the force that gravity exerts on an object. • Not constant

10. Units of Mass • Massis a measure of the quantity of matter present • Weight is a force that measures the pull by gravity- it changes with location • Mass is constant, regardless of location

11. Working with Mass • The SI unit of mass is the kilogram (kg), even though a more convenient everyday unit is the gram • Measuring instrument is the balance scale

12. Volume • Amount of space occupied by matter • 3 length measurements • Regular objects • L x W x H • Irregular objects • Water displacement method

13. Volume • The space occupied by any sample of matter. • Calculated for a solid by multiplying the length x width x height; thus derived from units of length. • SI unit = cubic meter (m3) • Everyday unit = Liter (L), which is non-SI. (Note: 1mL = 1cm3)

14. The Volume Changes! • Volumes of a solid, liquid, or gas will generally increase with temperature • Much more prominent for GASES • Therefore, measuring instruments are calibrated for a specific temperature, usually 20 oC, which is about room temperature

15. Rules in determining significant fiures 1. All non-zero digits are significant… Ex. 234.54 = 5 2. All zeros between two significant digits are significant. Ex. 20.01 = 4 3.All zeros to the left of an expressed decimal point and to the right of a significant digit are significant Ex. 7500. =4

16. 4. All zeros to the left of an implied decimal point and to the right of a significant digit are not significant.. Ex. 23,000,000 =2 5.All zeros to the right of the decimal point and to the right of a significant digit are significant digit are significant.. Ex. 0.000520 , 5.20 =3

17. Cont…… 6. All zeros to the right of the decimal point and not to the right of a significant digit are not significant Ex 0.000567 = 3 7. Zero with a bar above it is significant… Ex. 600 00Ō 00 = 3

18. Unit needed Given Unit X Unit to be canceled Metric English Conversion • Dimensional Analysis: • Identify the Given Unit • Identify the Unit Asked • Use appropriate conversion factor • Analyze and apply the conversion factor

19. Unit needed Given Unit X Unit to be canceled Metric English Conversion • Dimensional Analysis: • Identify the Given Unit • Identify the Unit Asked • Use appropriate conversion factor • Analyze and apply the conversion factor

20. Unit needed Given Unit X Unit to be canceled Metric English Conversion • Dimensional Analysis: • Identify the Given Unit • Identify the Unit Asked • Use appropriate conversion factor • Analyze and apply the conversion factor

21. 2.205 lbs 50 kg = X 1 kg Metric English Conversion • 50kg = _______ lbs 1kg = 2.205 lbs = 110.25 lbs

22. 1 in 12 cm = X 2.54 cm Metric English Conversion • 12 cm = _______ in 1in = 2.54 cm = 4.72 in

23. 1.06 qts 3.78 L 5 gal = X X 1 gal 1 L Metric English Conversion • 5 gal = _______ qts 1gal = 3.78 L 1L = 1.06 qts = 20.03 qts

24. 1000 m 1.61 km X = 9.3 x 107 mi X 1 mi 1 km Metric English Conversion • The earth has an average distance of 9.3 x 107 miles from the sun. How far is this in meters? • 9.3 x 107 mi = ______ meters 1 mi = 1.61 km 1 km = 1000 m = 1.50 x 1011 m

25. k h da o d c m Let’s practice: • 25.4 km = _____________ cm? • 5 places to the right • 2,540,000 cm 1 2 3 4 5

26. k h da o d c m Let’s practice: • In order to prepare a gelatin, one needs 250 mL of water. How much is this in Liters? • 3 places to the left • 0.25 L

27. Length 1 in = 2.54 cm 1 m = 3.28 ft 1 ft = 12 in 1 m = 1.09 yd 1 mi = 1.61 km 1km = 1000 m Mass 1 kg = 2.205 lbs 1 lb = 16 oz 1 g = 1000 mg Area 1 in2 = 6.45 cm2 1 m2 = 10.76 ft2 1 mi2 = 2.59 km2 Volume 1 gal = 3.78 L 1 L = 1.06 qts 1 in3 = 16.38 cm3 1 m3 = 35.3 ft3 1 tsp = 5 mL 1 L = 1000 mL Conversion Factors:

28. Conversion Factors: Time 1 min = 60 seconds (s) 1 hr = 60 minutes (min) 1 day = 24 hours (h) 1 year = 12 months (mon) 1 decade = 10 years (yr) 1 century = 10 decades 1 millenium = 10 centuries

29. 5ft = _____ m 40 m2 = _____ ft2 125 lbs = _____ kg 16 ml = _____ gal 5,300 ft = ____ in 247 cg = ____ dag 320 kL = _____ dL Practice Exercises: 1.52 x 100 m 4.30 x 102 ft2 5.67 x 101 kg 4.23 x 10-3 gal 6.36 x 104 in 2.47 x 10-1 dag 3.20 x 106 dL