1. MEASUREMENTS
Kenneth E. Schnobrich

2. WHAT DO WE HAVE TO DO? WE MUST DEFINE WHAT IT IS WE ARE GOING
TO MEASURE
2. WE MUST ESTABLISH A STANDARD
WE MUST DEVELOP SOMETHING TO COMPARE
TO THE STANDARD

3. NORMAL MEASUREMENTS
LENGTH
2. MASS
TIME
4. TEMPERATURE

4. Interval between 2 events
TYPICAL UNITS
UNIT
DEFINITION
STD
COMPARE
LENGTH
Dist. Between 2 points
Meter
Metric rule
MASS
Quantity of matter
grams or kilograms
Balance
TIME
Interval between 2 events
Second
Timer/clock
TEMP.
Measure of avg. K.E.
°C or K
thermometer

5. BASIC vs DERIVED
Basic Units or Fundamental Units are those we just mentioned
Length
Mass
Time
Temperature

6. BASIC vs DERIVED Derived Units are combinations of the basic units
Area L x W
Volume L x W x H
Density Mass/Volume
Energy Joule (kg•m2/s2) or calorie
Pressure Pa = kg/m•s2

7. WHY THE METRIC SYSTEM? • BASED ON DIVISIONS OF OR MULTIPLES OF TEN
• THERE ARE COMMON PREFIXES
• THE SYSTEM IS WIDELY ACCEPTED

8. COMMON PREFIXES Prefix Symbol Meaning Exp. Not. Mega M 1,000,000. 106
Kilo k
1,000.
103
Hecto h
100.
102
Deca D
10.
101
Deci d
0.1
10-1
Centi c
0.01
10-2
Milli m
0.001
10-3
Micro
10-6
Nano n
10-9

9. UNIT CONVERSIONS Convert 25.4 kg to g: Convert 8500 m to mm: 25.4 kg x
(1000 g/kg) =
25400 g
Convert 8500 m to mm:
8500 m x
(1000 mm/m) = mm

10. WHAT IS A SIGNIFICANT FIGURE?
When you are making a measurement there are
always a certain number of known or certain digits.
Then as part of the measurement there will always
be a digit that is uncertain because it is your guess.
The known or certain digits plus the first unknown
Digit are referred to as the SIGNIFICANT FIGURES

11. PRECISION vs ACCURACY
PRECISION: this refers to a situation where the same
result is gotten each time you perform the operation
• repeatedly hitting the same spot in darts
ACCURACY: this refers to how close you come to
the accepted value or result
• how close you are to the bullseye

12. SIGNIFICANT FIGURES The following rules apply to significant figures:
All digits in a measurement are considered significant
Zeros that fall between digits are considered significant
Zeros to the right of a decimal and to the left of a non-zero are considered significant
If a decimal point is placed after a zero all of the intervening zeros are significant
Zeros after a digit but not followed by a decimal are not significant

13. EXACT NUMBERS These are usually numbers that are obtained by
counting rather than using a measuring device
such as a buret or graduated cylinder - 12 eggs in a
dozen, 2 socks in a pair, 144 things in a gross

14. SIGNIFICANT FIGURES Working with Significant figures:
When you add or subtract numbers:
the final answer can have no more decimal places than the least precise value in the operation
2. When you multiply or divide numbers:
the final answer can have no more significant figures than the smallest number of significant figures in the operation

15. EXAMPLES ADDING & SUBTRACTING: 5.0043 4.032 1.02 3.2 5.0043 1.02 4.02
13.3

16. EXAMPLES
Multiplying and Dividing
4.91
5.0043
4.032
1.02
5.0043
20.33

17. MORE EXAMPLES How many Significant figures in each of the following:

18. MORE EXAMPLES How many Significant figures in each of the following:=
/4 =
x = = =

19. ROUNDING
When rounding use only the first digit to the right of the last significant figure becomes 4.3 if rounded to 2 sig.figs.
Rules:
In a series of calculations, carry the extra digits through to the final result, then round.
If the digit to be removed
Is less than 5 the preceding digit stays the same becomes 1.3
Is equal to or greater than 5, the preceding digit is increased by becomes 1.4