1. MEASUREMENTS, UNITS, and TOOLS

2. “I CAN” statements
critique that data represented with a number alone is meaningless. [L3] This means that I can cite evidences that data must always be reported with its numerical value and its appropriate unit.
distinguish between accurate and precise data [L2] This means that I can distinguish between data that are close to the accepted value and those that are all close to each other.
classify measurements as being fundamental (base), direct, or derived [L2] This means that I can relate a measurement to its specific unit.
recall visual aids for prefixes of mass and length [L1]

3. “I CAN” statements use the proper instruments to measure [L1] length,
volume liquid,
mass
weight
temperature This means that I can adequately measure and report data/values obtained with __ a ruler, __ a graduated cylinder, __ a triple beam balance, __ a spring scale __ a thermometer

4. “I CAN” statements calculate area and volume solid [L1]
solve density problems [L2] This means that I can modify the formula for density in order to estimate either volume or mass
infer how liquids will layer in a mixture based on their densities [L2]

5. “A science is as mature as its measurement tools” Louis Pasteur, 1822-1895
“To measure is to know” James Clerk Maxwell,  

6. Any data or value is expressed in terms of a NUMBER [magnitude, quantity] and a UNIT [describing the type of measurement]
A number alone is
MEANINGLESS

7. ACCURACY vs. PRECISION ? ?

8. ACCURACY vs. PRECISION
ACCURATE  measurement(s) is (are) close to the accepted values
PRECISE  repeated measurements are close to each other

9. PRECISE BUT LOW ACCURACY
ACCURACY vs. PRECISION
PRECISE BUT LOW ACCURACY

10. HOW WOULD YOU REPRESENT?
ACCURATE and PRECISE

11. HOW WOULD YOU REPRESENT?
NEITHER ACCURATE, NOR PRECISE

12. In science, you must aim to collect data that are both accurate AND precise

13. BASE/FUNDAMENTAL, “DIRECT”, and DERIVED MEASUREMENTS

14. Base and/or “Direct” Measurements
Physical Quantity
Name of Unit
Symbol
Length
meter m
Mass
gram g
Time
second s
Temperature
kelvin K
Electric current
Ampere D
Amount of substance
mole
mol
Luminous intensity
candela cd
* Volume Liquid
Liter L
A base unit is ALWAYS directly measured, but a direct measurement is not necessarily a base unit

15. Time  second
Mass  gram
Temperature  Kelvin
Length  meter

16. NOTICE THE ABBREVIATIONS: prefix and unit
LENGTH
= Distance from one point to another
The base unit for length is METER [m]
1 kilometer [km] = 5 – 6 city blocks
1 meter [m] = from floor to door handle
1 centimeter [cm] = width of little finger
1 millimeter [mm] = width of a dime / pencil lead
NOTICE THE ABBREVIATIONS: prefix and unit

17. 16 divisions per inch
1/16th
1/8th
1/4
1/2

18. 10 divisions per centimeter
1/10th or 0.1cm or 1 mm

19. State the same measurement
in two different units
Length
10 in.
260 mm 26.0 cm

20. MASS [not to be confused with WEIGHT]
= amount of MATTER that an object has or contains
The base unit for mass is the GRAM [g]
1 kilogram [kg] = house brick
1 gram [g] = 1 small paper clip
454 grams [g] = 1 pound
NOTICE THE ABBREVIATIONS: prefix and unit

21. Triple –beam Balance 80
200
0.6 6
= grams

22. 70
300 6
= grams

23. 30
300 4
0.5
= grams

24. TEMPERATURE
= average kinetic energy of the particles in a substance, related to how hot or cold it is
Fahrenheit °F
Water boils
212
Scale of 180
Water freezes 32

25. TEMPERATURE
Metric System uses primarily Celsius [°C], but it is NOT the base unit
Fahrenheit
Centigrade °F °C
Water boils
212
100
Scale of 180
Scale of 100
Water freezes 32

26. SI unit Kelvin [K] = thermodynamic temp.
TEMPERATURE
SI unit Kelvin [K] = thermodynamic temp.
Note no degree symbol for Kelvin
Note 1 Kelvin = 1 °Celsius
Fahrenheit
Centigrade
Kelvin °F °C K
Water boils
212
100
373
0K is the absolute zero. Even the atoms are stopped
Scale of 180
Scale of 100
Water freezes 32
273

27. TEMPERATURE [˚C]
87.5°C
35°C

28. Volume liquid can be “directly” measured with the proper instruments
What could be used to evaluate the volume of a liquid?
2 Liters

30. NOTICE THE ABBREVIATIONS: prefix and unit
VOLUME LIQUID
= Amount of SPACE that a liquid occupies
The unit without prefix for volume liquid is LITER [L]
4 liters [L] = 1 gallon
355 milliliter [mL] = 12 ounces
NOTICE THE ABBREVIATIONS: prefix and unit

31. 53 mL 1mL Graduated cylinder; 0 at the bottom 10 mL graduation
Always read the BOTTOM of the MENISCUS
1mL
SO EACH SUB-DIVISION IS WORTH:

32. What do you see??
11.5 mL

33. 76 mL

34. 3.7
4.9
3.3

35. 7.7
5.4
3.1

36. 4.7
4.2
6.6

37. Units/Measurements that are found by making CALCULATIONS
DERIVED UNITS
Units/Measurements that are found by making CALCULATIONS
AREA: the SURFACE of an object Formula = Length x Width Example: if you measure in meter, what will the unit be for the area??
NOTE: both dimensions / measurements must be in the same units

38. Numerical value 5 m 10 m AREA = 5 m x 10 m = 50 m2
The ‘derived’ unit is read as square meter or meter squared
10 m
AREA = 5 m x 10 m = 50 m2
Numerical value

39. DERIVED UNITS
VOLUME solid: the SPACE that an object occupies or contains. Formula = Length x Width x Height Example: if you measure in centimeter, what will the unit be for the volume??

40. 3 cm 5 cm 15 cm VOLUME = 3 cm x 5 cm x 15 cm = 225 cm3 Numerical value
The ‘derived’ unit is read as “cubic centimeter”…
Numerical value

41. So 1mL is equivalent to 1cm3
VOLUME and LENGTH are linked
1 cubic centimeter = 1 milliliter
1 mL of any liquid occupies [fills] a small container measuring 1cm by 1cm by 1 cm
1 cm
So 1mL is equivalent to 1cm3
1 cm
1 cm
So 1 Liter (L) occupies ???? cm3

42. Volume Solid
But what would you do to know how much space is occupied by an irregular object like a rock??

43. Volume Displacement A solid displaces an equivalent volume of water.
50 mL
35 mL

44. Volume Displacement
So this object occupies: End volume – Start volume
50 mL – 35 mL = 15mL or 15 cm3

45. DERIVED UNITS
FORCE: a push or a pull affecting the motion of an object  2nd Newton’s Law of Motion F = M x A; kg x m/s^2
referred to as
Newton (N)

46. WEIGHT It is a FORCE. The force exerted by gravity on any object.
While Mass does NOT vary with location, WEIGHT varies depending on the gravitational pull.
Where do you weigh the most? On the moon, or on Earth????

47. DERIVED UNITS
4. DENSITY: how tightly the matter of an object is packed into a given volume  It is an important physical property Which one weighs more, 1 kg of feather or 1 kg of nails??? Which one is less dense?

48. The mass is the same -1 kg- , but their volumes -the space that they occupy- are different The feathers occupy more space, so they are less dense

49. DERIVED UNITS
DENSITY
Formula = Mass divided by Volume Example: if the mass of your book is given in grams and its volume in cubic cm,
what will the unit be for its density??

50. Mass = 300 g Volume = 60 cm3 DENSITY = 300 grams 60 cubic centimeter
= 5 g/cm3
Science
Divide numbers to get the numerical value
Divide units to get the final derived unit

51. DENSITY = 5 g/cm3 This derived unit is a new, more complex unit
Science
The ‘division’ slash is read as “per”…; meaning “for every”

52. 13.6 g/cm3 19.3 g/cm3 2.7 g/cm3 2.75 g/cm3 0.0013 g/cm3 Aluminum GOLD
Mercury
13.6 g/cm3
GRANITE
2.75 g/cm3
AIR
g/cm3

53. HIDE WHAT YOU ARE LOOKING FOR TO FIND THE RIGHT FORMULAV
multiply

54. HIDE WHAT YOU ARE LOOKING FOR TO FIND THE RIGHT FORMULA
divide D V

55. HIDE WHAT YOU ARE LOOKING FOR TO FIND THE RIGHT FORMULA
divide D V

56. HIDE WHAT YOU ARE LOOKING FOR TO FIND THE RIGHT FORMULA
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3.
What is the mass of 95 mL of Hg in grams? M
HIDE WHAT YOU ARE LOOKING FOR TO FIND THE RIGHT FORMULA D V

57. REMEMBER: 1 cm3 = 1 mL

58.
 see Tab 6 for word problems
 Worksheets Chap2, 2-7a thru g

59. Problem A piece of copper has a mass of 57. 64 g. It is 9
Problem A piece of copper has a mass of g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3). M
8.96 D V

60. Osmium is a very dense metal: 22. 5 g/cm3
Osmium is a very dense metal: g/cm3. How much volume does 50 g of Osmium occupy?
2.22 cm3
22.5 cm3
111 g/cm3

61. Which choice correctly represents the liquid layers in the cylinder
Which choice correctly represents the liquid layers in the cylinder? [from top to bottom] (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL), (W) water (1.0 g/mL)
V, W, K
W, K, V
K, V, W

62. K V W 1)
0.91
1.0
1.4

63. A measurement that is accurate is one that
Is as exact as possible
Is close to the true value
Contains at least four digits after the decimal point
None of the above

64. What is the density (g/cm^3) of 48g of an unknown metal if the object raises the level of water in a graduated cylinder from 30mL to 54mL?
0.48 g/cm^3
20 g/cm^3
1.3 g/m^3
2.0 g/cm^3
 54 mL
30 mL 