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Measurements

Measurements. Why do we need to measure?. to learn about the universe to help others to glorify God and help subdue the earth. Measurement. is the act of comparing an unknown quantity to a standard unit of measurement. Instruments. The standard is a known quantity.

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Measurements

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  1. Measurements

  2. Why do we need to measure? • to learn about the universe • to help others • to glorify God and help subdue the earth

  3. Measurement is the act of comparingan unknown quantity to a standard unit of measurement.

  4. Instruments • The standard is a known quantity. • An instrument is a device used to help our senses when measuring. • An instrument is calibrated. It has marks on it that are spaced out.

  5. 2 Types of Data Qualitative—uses description, no numbers(Examples: larger, red, increases) Quantitative—uses numbers(Examples: 3 feet, 25 miles/hour)

  6. Measured Data • Measurements MUST include numbers and units! • What does “I ran 7” tell you?

  7. Counting Number • Uses only a quantity; NO measured unit. • Counted number – a number that is counted

  8. Scientists Prefer • Quantitative Data • Easy to check • Easy to agree upon • No personal bias • Limited by measuring instrument.

  9. The Metric System • first established in France and was followed voluntarily in other countries • adopted by most of the world in 1960 in the form of the SI (Système International d’Unités)

  10. The Metric System • Every unit has two parts: • Prefix • Base

  11. The 7 SI Base Units

  12. The Metric Standard • based on the meter and kilogram • The standard for the meter used to be an object, but it is now based on a length of light. • Most standards are no longer physical • The exception: kilogram

  13. Metric Prefixes

  14. Conversion Factors • any factor equal to 1 that consists of a ratio of two units • You can find many conversion factors in the Appendix of your textbook.

  15. Unit Analysis Dimensional Analysis First, write the value that you are given.

  16. Unit Analysis Next, multiply by the conversion factor, which should be written as a fraction. 1 dozen 12 60 eggs × eggs Note that the old unit goes in the denominator.

  17. 1 dozen 12 eggs Unit Analysis Then cancel your units. 60 eggs × Remember that this method is called unit analysis.

  18. 1 dozen 12 60 eggs × eggs = 5 dozen Unit Analysis Finally, calculate the answer by multiplying and dividing.

  19. Sample Problem Convert 160 pounds to ounces. First, write the value that you already know. 160 lbs

  20. Sample Problem Convert 160 pounds to ounces. Next, multiply by the conversion factor, which should be written as a fraction. 1 lb 160 lbs × 16 ounces To cancel, be sure that the old unit is in the denominator. WHAT IS WRONG?

  21. Sample Problem 16 ounces 160 lbs × 1 lb Convert 160 pounds to ounces. Now cancel the units.

  22. Sample Problem 16 ounces 2560 ounces 160 lbs × = 1 lb Convert 160 pounds to ounces. Finally, calculate the answer by multiplying and dividing.

  23. Sample Problem #2 1 km 1000 m × 13.4 km = Convert 13400 m to km. 13400 m

  24. Sample Problem #3 1000 mL 1 L × = 2000 mL How many milliliters are there in a 2 L soft drink bottle? 2 L

  25. Sample Problem #4 1000 g 1 kg × = 3500 g Which contains more mass, a 350 g box of chocolates or a 3.5 kg box of chocolates? 3.5 kg The 3.5 kg box contains much more chocolate!

  26. Sample Problem #5 7 d 1 wk 24 h 1 d 60 min 1 h × × × = 604,800 s 60 s 1 min × How many seconds are in a week? 1 wk

  27. Sample Problem #6

  28. Sample Problem #6 1 mi 1.6 km ≈ × 21.9 mi Convert 35 km to mi, if 1.6 km ≈ 1 mi. 35 km

  29. Sample Problem #7 1.6 km 1 mi ≈ × 8.0 km Convert 5.0 mi to km, if 1.6 km ≈ 1 mi. 5.0 mi

  30. Convert 120 km to mi, if 1.6 km ≈ 1 mi. • 120 mi • 75 mi • 180 mi • 120 km Question

  31. Convert 120 km to mi, if 1.6 km ≈ 1 mi. 1 mi 1.6 km ≈ 120 km × 75 mi Question

  32. Measurements must include • a conversion factor. • quantitative data. • an instrument. • numbers and units. Question

  33. Measurement is the act of comparing an unknown quantity to a standard unit of measurement. T / F Question

  34. Measurementof Matter

  35. Weight • does not directly indicate the amount of matter • is a measure of the earth’s gravity attracting an object • can change from place to place

  36. Weight • Measured in Newtons. • Kg• m • s2 • One pound equals approximately 5 newtons.

  37. Weight Weight is measured with a spring scale or an electronic scale.

  38. Mass • indirectly indicates the amount of matter • is measured in grams

  39. Mass It is measured with a mass balance or just a balance.

  40. Mass • Examples: • 1 mg = 10 grains of salt • 1 mg = 2 drops of water • 1 g = 1 paper clip • 1 kg = 2.2 lbs

  41. Mass Mass can also be measured by inertia, a property that will be discussed later.

  42. T/F The weight of an object and the mass of an object are always equal. F Question

  43. Volume the amount of space occupied by an object

  44. Volume • Measured in Liter • If an object is geometrically simple, its volume can be calculated from a formula.

  45. Volume • The volume of a cube = (side length)3. • If a cube has sides of 1 m, then its volume is 1 m × 1 m × 1 m, which is 1 m3. • Note: multiply the units.

  46. Volume • 1 m3 is the SI unit for volume. • This SI unit istoo large for most of the labs. 1 m 1 m 1 m

  47. Metric Volume A cube with sides measuring 1/10 meter (10 cm) has a volume of one liter (slightly larger than a quart). 10 cm 10 cm 10 cm

  48. Metric Volume • Divide the 10 cm length of a side of a liter into 10 parts (1 cm each). • This makes a cube with sides 1 cm long, so the cube has a volume of 1 cm3.

  49. Metric Volume • 1 cm3 is 1/1000 of a liter, so it is also called 1 mL. • 1 cm3 = 1 mL • A mL is also called a cc, which stands for cubic centimeter. • 1 mL is about 20 drips of water or 1 sugar cube.

  50. 1 cm3 10 cm 10 cm 10 cm

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