Transcript Types of Measurements

Types of Measurements:
Different Measurements
By Tiffany and Samantha
Qualitative
Quantitative
The appearance of a sample in words
(QUALITY)
The amount with numbers (QUANTITY)
Ex. Cold, Light, etc.
Ex. 18.3 cm, 10g, 4 min.
SI Units are used to measure in science
• Temp.
K
Kelvin
• Length
M
Meters
• Mass
Kg
Kilograms
• Volume
L
Liters
• Time
S
Seconds
Good Measurements are true (accurate) and repeatable (precise)
Can you make a qualitative
and quantitative measurement
of the following?
.5 grams
20 grams
Accuracy and Precision:
Information
By charlie zoeller, John Cornfield,
& dylan Brooke
• When measuring, a measurement should be
true and repeatable.
• This means that the information is accurate
and precise.
Sample
•A textbook says that the density of an object is
10g/cm^3 but a student finds out its actually
8g/cm^3.
• Is it accurate?
Yes- The student measured all sides of the book
and multiplied them to get
8g/cm^3
– Is it repeatable?
» No- Both the textbook and the students had different
answers
Practice Problem
• Student one measures a sample of iron to be
3.34 g. Students two and three measure it to
be 3.3g. Is student one correct?
Practice problem
• Yes, although the student rounded, the info is
precise and accurate.
Sig Figs in Measurements
By Ian Quinn, Brian Sayre, and Jack
Weinberger
• Significant Figures are used to reduce the
amount of guessing when making
measurements.
• When measuring, you take all of the certain
numbers, plus 1 estimated number.
Measuring using Sig Figs
• The last certain number on
this graduated cylinder is
to the tens place.
• We are certain that it goes
to 17, but we have to take
1 estimated number past
the last certain number. So
we would get a
measurement of 17.1
Measure the leaf, with Sig Figs!
3.59 cm
Multiplying and Dividing SigFigs: Rules
Mackenzie Saturn, Leah Edmonds and
Katelyn Ewell
• When multiplying and dividing, the number of
SigFigs in your answer is the same as the least
number of SigFigs in your measurement.
Examples-Multiplication
Questions:
1. 250.mL x 5.6mL
2. 50.54cm x 30cm
3. 0.25g x 45g
Answers:
1. =1400mL^2
2. =2000cm^2
3. =11g^2
Examples-Division
Questions:
1. 50.54cm
4.1mL
2. 1.278 x 10^3m
1.4267 x 10^2m
3. 7530g / 6.5g
Answers:
1. =12cm/mL
2. =8.958m
3. =1200g
Try it!
Questions:
1. 8.91 x 2700
2. 5000. x 0.23
3. 2.90
1.7
4. 678
4
Answers:
1. =24000
2. =1200
3. =1.7
4. =200
Metric Prefix Conversions
By: Julia Broadbent and Carolyn Belardinelli
What is a Prefix?
• Prefixes are used to adjust the size of a metric
unit.
Positive Prefixes
•
•
•
•
•
•
Tera: T-10^12 (1,000,000,000,000)
Giga: G-10^9 (1,000,000,000)
Mega: M-10^6 (1,000,000)
Kilo: k-10^3 (1,000)
Hecto: h-10^2 (100)
Deca: da-10^1 (10)
Base Units
• Grams, Liters, Meters, etc.
• They equal 1 unit
Negative Prefixes
•
•
•
•
•
•
Deci: d-10^-1 (.1)
centi: c-10^-2 (.01)
milli: m-10^-3 (.001)
micro: -10^-6 (.0000001)
nano: n-10^-9 (.0000000001)
pico: p- 10^-12 (.0000000000001)
Sample Problems
1) 1nm=10^-9m
2) 14cm*10^-2m =1.4*10^-1m
1cm
-write down # and unit given
-put units to get rid of in denominator. Put units
wanted in numerator
-fill in the equality with correct units
Other Unit Conversions:
Information/ How To
by Mark And Mike
• Converting a unit of measure to another unit
of measure such as: inches-miles.
Sample Problem
• 3 feet=1 yard
• 12 feet to___ yards.
• 12 feet/ 3 feet
1 yard
• Answer= 4 yards
Practice Problem
• ¼ mile= 15,840 inches
• 100,000 inches to ____ miles.
Answer
• 1.57 miles
What is Density?
Maria Weck & Jessica Chu
•
•
•
•
Density is a ratio of mass to volume
Density can be used to identify substances.
The density of a substance is always the same.
You can find density by dividing mass by
volume.
• The units of each are… density=g/cm^3 or
g/mL, mass=g, volume=cm^3 or mL
Sample Problem
• If a 96.5g newspaper has a
density of 2.7 g/cm3, what is
its volume?
•V=M÷D
Answer
•V= 35.74 cm^3
Percent Error
By Daniel Yu and Julian Wolak
• Percent error is stated as a percentage of the
change between an approximate or measured
value and an exact or known value.
• To calculate Percent error, you must use this
formula:
|Accepted Value-Experimental Value|
Accepted Value x 100%
Sample Problem
You calculate the density of an aluminum block
and it is 2.68 g/cm3. Then you calculate the
density in room temperature and the density is
2.70 g/cm3. Calculate the percent of error.
Sample Problem
2.68 – 2.70
2.70 X 100%
.02/ 2.70= .0074074
.0074074 X 100% = .74%
Percent of Error is .74%
(expressed using 2 SigFigs)
Problem
• At a track meet, you time a friend running 100
m in 11.00 seconds. The officials time her at
10.67 seconds. What is your percentage
error?
Answer
10.67-11.00 = -.33
.33/10.67= .03093 X 100%
Percent of error is 3.08%