Post on 12-Jan-2016
Types of Measurements: Different Measurements
By Tiffany and Samantha
Qualitative Quantitative
The appearance of a sample in words (QUALITY)
Ex. Cold, Light, etc.
The amount with numbers (QUANTITY)
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 MeasurementsBy 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: RulesMackenzie 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 5.6mL2. 50.54cm x 30cm3. 0.25g x 45g Answers:
1. =1400mL^22. =2000cm^23. =11g^2
Examples-Division
Questions:1. 50.54cm 4.1mL2. 1.278 x 10^3m 1.4267 x 10^2m 3. 7530g / 6.5g
Answers:1. =12cm/mL 2. =8.958m3. =1200g
Try it!
Questions:1. 8.91 x 27002. 5000. x 0.233. 2.90 1.74. 678 4
Answers:1. =240002. =12003. =1.74. =200
What is a Prefix?
• Prefixes are used to adjust the size of a metric unit.
Metric Prefix ConversionsBy: Julia Broadbent and Carolyn Belardinelli
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 ErrorBy 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 – 2.702.70 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%