1. Chapter 1 Scientific Measurement

2. 1) A system of measure-ments is a set of units which can be used to specify any-thing which can be measured.

3. 2) What are the 2 most common systems used in the world?
Standard (Customary, English, British , Imperial, or US) system.
Metric (International system, or SI)

4. 3) Which system do you know the best?
Lets check your measurement IQ.
What is our (US customary system) smallest unit of distance?

5. Inch? (barley corn ? king’s thumb)
Pica (1/6 in)
Angstrom (~4 billionths of an in)
Hand (4 in)
Foot (12 in)
Cubit (18 in)
Pace ??? (25 in- 40 in)

6. Yard (36 in or 3 ft)
Fathom ( 6 ft)
Rod (16½ ft)
Chain (66 ft)
Furlong (660ft)
Mile (statuate, nautical, admiralty, USCS) ft, 6067 ft, 6080 ft, 6080 ft & 4 in
League (~3miles)
Astronomical unit (~ 93 million miles)
Light-year (~ 6 trillion miles)
Parsec (~19.2 trillion mi or 3.26 LY)

7. 4) Which system is easiest to use?
METRIC SYSTEM!!!
Based on 10’s
Uses decimals
Only 7 base units
Uses prefixes to change unit size

8. 5) Which system is best for world trade?
Metric system (SI)
Used by every country in the world but the USA
Cost efficient.
The English system is costing us money!!!!

9. 6) Which system is the most accurate & precise?
Metric System (SI)
Easier to use.
All units are based on science.
Most scientific instruments are calibrated with metric units.

10. Do you want to talk about weight or time?
Is the metric & standard seconds the same?
Which is better weight or mass?

11. 8) Which system is best for science?
Metric system
easier / logical
Accurate / precise
Invented by scientist for science!
Invented in 1600’s by Gabriel Mouton.

12. UNITS are dimensions, any specified amount of a quantity.
Physical Quantity Base UNIT Symbol
Distance (d) meter (m)
Mass (m) kilogram (kg)
Time (t) second (s)
Temperature kelvin (K) (T)

13. Electric (I) ampere (A) current Amount of (N) mole (mol) substance
More base units
Quantity Base UNIT (Symbol)
Electric (I) ampere (A) current
Amount of (N) mole (mol) substance
Luminous (l ) candela (cd) intensity

14. Do you have ERROR in your measurements?
Error is the difference between the measured value & the accepted (actual value)
What causes error?

15. Types of Error Human-> Carelessness, misreading, miscalculations
Equipment-> calibrations, zero, poor quality
System-> the way you acquire your measurements

16. Accuracy Refers to the closeness of measurement to the accepted value.
Accuracy can be expressed in terms of error.

17. Absolute vs. Relative Absolute error = observed – actual or Ea = [O-A]
Relative error = absolute/actual & it is expressed as a percentage Er = [O-A] / A x 100

18. Precision
is the agreement among several measurements made the same way. The exactness of your measurements.
It can be expressed in terms of deviation.
Significant figures.

19. Is accuracy and precision the same?
Let’s use a golf analogy.

20. Accurate? No
Precise?
Yes

21. Accurate?
Yes
Precise?
Yes

22. Precise? No
Accurate?
Maybe?

23. Accurate?
Yes
Precise?
We can’t say!

24. Why do I have to learn this stuff?
Sig figs are only for precision & they only apply to measurements.
You won’t use them in math class because math is theory. Numbers can represent anything.
Calculators can not make your measurements more precise!!
Examples:
How many students are at HHS?
How much do you still owe me?

25. Significant figures (sig figs)
How many numbers mean anything.
When we measure something, we can (and do) always estimate between the smallest marks. 2 1 3 4 5

26. SIG FIG Rule #1 A) 567 456 123 m B) 798 465 mol C) 45 A
All non-zeroes are significant.

27. SIG FIG Rule # 2 A) 567 000 123 km B) 798 005 W C) 405 cd
All zeroes between sigfigs are significant.

28. SIG FIG Rule # 3 A) 476 000 g B) 40 N C) 16 000 000 000 L
All zeroes (that are place holders) to the left of an understood decimal place are NOT significant.

29. SIG FIG Rule # 4 mg s
mol
All zeroes (that are place holders) to the right of a decimal place are NOT significant.

30. SIG FIG Rule # 5 A) 1100. 0 K B) 12.00 m C) 0. 000 500 mol
All zeroes added to the end of a measurement to insure precision are significant.

31. SIG FIG Rule # 6
A) 800 ms
B) N
C) g
All zeroes with a bar above them in the measurement are significant.

32. A) Report 100 000 g/mL to 3 sigfigs
B) Report mol to 7 sigfigs
C) Report C to 5 sigfigs

33. Addition+-Subtraction Rule #7
Number with fewest decimal places determines the sigfigs in answer.
A) m m m = ???
B) s s = ????
C) A A A = ????

34. Multiplication/Division Rule # 8
Number with fewest sigfigs determines the sigfigs in answer.
A) W x W x 100 W = ????
B) 1200 mol x mol = ????

35. Are you ready for the rounding rules?
C) 11.6 m / m = ????
D) 1000 s / s = ????
Are you ready for the rounding rules? .

36. Rounding Rule #1
A) If the first nonsignificant number to the right is less than 5, drop all the nonsignificant numbers only. Round down.
Example: Round cm to 3 sigfigs
73.5 cm 

37. Rounding Rule #2
B) If the first nonsignificant number to the right is greater than 5, drop all the nonsignificant numbers and add 1 to the last significant figure on the right. Round up
Example: Round cm to 2 sigfigs
1800 cm 

38. Rounding Rule #3 The even or “ODD” Rule
B) If the first nonsignificant number to the right is equal to 5, drop all the nonsignificant
round up if odd or
drop remainder if even
Why?

39. WHY ????????
A) Round to 3 sigfigs
2.54
Round to 3 sigfigs

40. Significant figures (sig figs)
The better marks the better we can estimate.
Scientist always understand that the last number measured is actually an estimate. 1 2 3 4 5

41. Significant figures (sig figs)
The measurements we write down tell us about the ruler we measure with
The last digit is between the lines
What is the smallest mark on the ruler that measures cm?
141
142

42. Significant figures (sig figs)
What is the smallest mark on the ruler that measures 142 cm?
100
200
150
250 50

43. 140 cm?
100
200
150
250 50
100
200
Here there’s a problem is the zero significant or not?

44. 140 cm?
100
200
150
250 50
100
200
They needed a set of rules to decide which zeroes count.
All other numbers do count.

45. Which zeros don’t count as sig figs?
Those at the end of a number before the decimal point don’t count.
12400
If the number is smaller than one, zeroes before the first number don’t count.
0.045
These zeros are only place holders

46. Which zeros do count as sig figs?
Zeros between other sig figs do.
1002
Zeroes at the end of a number after the decimal point do count.
If they are holding places, they don’t.
If they are measured (or estimated) they do.

47. 100
200
150
250 50
100
200

48. Problem 50 is only 1 significant figure.
if it really has two, how can I write it?
A zero at the end only counts after the decimal place.
Scientific notation.
5.0 x 101
now the zero counts.

49. 1.40 x 102 cm
100
200
150
250 50
140 cm
100
200

50. Sig figs. How many sig figs in the following measurements? 458 g

51. Rounding rules Look at the number behind the one you’re rounding.
If it is 0 to 4 don’t change it.
If it is 5 to 9 make it one bigger.
Round to four sig figs.
to three sig figs.
to two sig figs.
to one sig figs.
45.46
45.5 45 50

52. Numbers without sig figs
Counted numbers
12 eggs in a dozen
32 students in a class
Definitions
1 m = 100 cm
16 ounces is 1 pound
No estimated numbers
Unlimited significant figures

53. Scientific Notation
Science often deals with very large and very small numbers.
There are 33,400,000,000,000,000,000,000 molecules of water in 1.00 mL
one electron has a mass of g
We need an easier way of writing these numbers.

54. Standard Exponential Form
another name for scientific notation.
consists of two part
a number between 1 and 10
Order of magnitude, indicated by a power of 10
Examples
602,000,000,000,000,000,000,000 = x 1023
g= x 10-28

56. Scientific notation
All non-zero digits in scientific notation are significant figures.
Any ending zero will be after the decimal point to be significant
1.20 x 103
Sometimes you must write in scientific notation to use the correct sig figs.

57. Putting a number into scientific notation
determine how many times you have to move the decimal place to make it into a number between 1 and 10
use that as the power of 10
3.24 x 106

58. What if the number is smaller?
if you make the number bigger by moving the decimal point, make the exponent smaller and visa-versa
4.5 x 10-4

59. Watch the Sig Figs
When rounding, you don’t change the size of the number.
You should end up with a number about the same size.
Use place holders- they’re not significant.
Round to 3 sig figs
Round to 3 sig figs
15300
0.0290

60. Using your calculator with scientific notation
EE and EXP button stand for x 10 to the
4.5 x 10-4
push 4.5
push either EXP or EE
push 4 +/- or -4
see what your display says.