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DATA Metric System (SI) Taking Measurements Organization PresentationPowerPoint Presentation

DATA Metric System (SI) Taking Measurements Organization Presentation

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### DATAMetric System (SI) Taking MeasurementsOrganization Presentation

Data

- Your data are all the records you have gathered from an investigation.
- The types of data collected depend on the activity.
- Data may be a series of weights of volumes, a set of color changes,
- or a list of scientific names.
- No matter which types of data are collected, all data must be treated
- carefully to ensure accurate results.

- Sometimes the data seem to be wrong, but even then,
- they are important and should be recorded accurately.
- Remember that nature cannot be wrong,
- regardless of what you discover in the laboratory.
- Data that seem to be “wrong” are probably the result of the experimental error.

Metric System

- A decimal system of measurement whose units are based on certain physical standards and scaled on multiples of ___
- Based on units of 10

ten

Metric System

- Kilo (k) = 1000
- Hecta (h) = 100
- Deka (D) = 10
- Base = 1
- Deci (d) = 0.1
- Centi (c) = 0.01
- Milli (m) = 0.001

The system is easy to use because it is based on multiples of 10

1 meter = 100 cm

1 kilogram = 1000 grams

1 gram = 1000 milligrams

1 liter = 1000 milliliters

1 kilometer = 1000 meters

1 centimeter = 10 millimeters

Measurement in Science

- Scientists use a revised form of the metric system called
Le Systeme International d’Unites(International System of Units) or SI Units

S.I. Base Units

The International System of Units (S.I.) defines seven base units for the seven base quantities:

Length

- The distance from one point to another
- Meter – the SI unit of length
- Tool used to measure length depends on the size of the object
- Larger objects (i.e. the room)
- – meter stick

- Smaller objects (i.e. pencil length)
- – centimeter ruler

- Larger objects (i.e. the room)

Frequently used SI units

1 millimeter (mm) = 1000 micrometers (mm)

1 centimeter (cm) = 10 millimeters (mm)

1 meter (m) = 100 centimeters (cm)

1 kilometer (km) = 1000 meters (m)

1 light-year = 9,460,000,000,000 kilometers (km)

Length

Measuring Length

- Measure the distance from Point A to B
- What distance is Point A? Point B?
- What is the total distance between points?

4.5 cm

6.4 cm

6.4 cm – 4.5 cm =

1.9 cm

Mass

- The amount of matter in something
- Mass is measured using a balance or triple beam balance
- Or an electronic balance

Mass

However, some measurements of mass like the mass of vitamins or medicines are so small that we use milligrams (mg) to measure their mass

- The SI unit for mass is the kilogram (kg)
- The gram is the base unit

Frequently used SI units

1 gram (g) = 1000 milligrams (mg)

1 kilogram (kg) = 1000 grams (g)

1 metric ton = 1000 kilograms (kg)

Mass

Area

- Area is a physical quantity expressing the size of a part of a surface.
- The term can also be used in a non-mathematical context to be mean "vicinity".
- Surface area is the summation of the areas of the exposed sides of an object.

Frequently used SI units

1 square meter (m2) = 10,000 square centimeters (cm2)

1 square kilometer (km2) = 1,000,000 square meters (m2)

Area

Measuring Area

- Area = Length x Width

1 cm

The square has an area of 4 square

centimeters (4 cm2)

1 cm

Area = l x l2

= 2 cm x 2 cm

2 cm

Area = 4 square centimeters (4 cm2)

2 cm

Measuring Area

- Calculate the area of the following rectangles

2 cm

3 cm

cm

5 cm

8 cm

Area =

2 cm X 5 cm

Area =

3 cm X 8 cm

Area =

10 cm2

Area =

24 cm2

Volume

- The amount of space a substance takes up
- Volume of a liquid is found using a graduated cylinder
- Unit is liters (L) or milliliters (mL)

Frequently used SI units

1 milliliter (mL) = 1 cubic centimeter (cc) or (cm3)

1 liter (L) = 1000 milliliters (mL) or 1 dm3

Volume

Measuring Volume

- Liquid volume measured using graduated cylinder

- Read volume at meniscus ( downward curve of water)
- What is the volume of this liquid?
- 45 mL

Volume

- Volume of a solid is found using the volume equation
- length x width x height
- In this equation, we are also multiplying the units together so units for the volume of a solid are…
- m x m x m = m3 OR cm x cm x cm = cm3
- Also know that 1 mL = 1 cm3 = 1 cc (cubic centimeter)

Measuring Volume

- Solid volume measured using volume equation (l x w x h)

What is the volume of a cube

that is 2 cm x 2 cm x 2 cm?

Volume = l1 x l2 x l3

= 2 cm x 2 cm x 2 cm

Volume = 8 cubic centimeters (8 cm3)

Measuring Volume

- Calculate the volume of the box

Volume =

l x w x h

Volume =

6 mm X 5 mm X 2 mm

6 mm

Volume =

60 mm3

2 mm

5 mm

Water Displacement

- Some solid samples, such as an irregularly shaped rock cannot have their volume measured easily by using the volume equation (length x width x height)
- For these solids, scientists use a technique called Water Displacement

Water Displacement

- Steps of Water Displacement
- 1. Add water to a graduated cylinder and record its volume (ex: 7 ml)
- 2. Place the irregularly shaped solid into the graduated cylinder already containing water and record the new volume (ex: 9 ml)

Water Displacement

- 3. Subtract the smaller volume(combined volume) from the larger volume (water only) to get the volume of the irregularlyshaped solid. (ex: 9 ml – 7 ml = 2 ml)
- 4. We would say that the irregularly shaped solid takes up 2 ml of space. Since it is a solid, we need to state the volume using cm3 so we would say that its volume is 2 cm3

Temperature

- The amount of heat in something
- Tool used to measure temperature is a thermometer
- Celsius is the unit of measure in the metric system

Temperature

- SI unit for temperature is the Kelvin (K)
- Notice that there is no degree sign used!
- Kelvin scale is easier for scientists to use
- To calculate Kelvin you add 273 to the Celsius temperature
- Ex. 23 ○C = 23 + 273 = 296 K

-5

30

-5

-10

-10

25

-10

-15

-15

20

-15

Reading a Thermometer- What’s the temperature?

-5

-10

-15

-14.0 ○C

-14 ○C

24.5 ○C

Time

- The period between 2 events
- The SI unit of time is the second (s)
- Measurement tool of time is a stopwatch

Recording and Organizing Laboratory Data

- There are many ways to record and organize data, including:
- data tables, charts, and graphs.

- It is important to include the appropriate units when you record data.
- Remember that DATA are measurements or observations, not merely numbers.
- Data tables, graphs, and diagrams should have descriptive titles to ensure that
- another person can understand them without having been present during the
- investigation.

Many important scientific discoveries have been made accidentally in the

course of an often unrelated laboratory activity. Scientists who keep very

careful and complete records sometimes notice unexpected trends in and

relationships among data long after the work is completed. The laboratory

notebooks of working scientists are studded with diagrams and notes;

every step of every procedure is carefully recorded.

Data Tables and Charts

Data tables are probably the most common means of recording data.

Although prepared data tables are often provided in lab manuals, it is

important that you be able to construct your own. The best way to do

this is to choose a title for your data table and them make a list of the

types of data to be collected. This list will become the headings for

your data columns.

For example, if you collected data on plant growth that included both

the length of time it took for the plant to grow and the amount of growth,

you could record your data in a table (as shown below).

Example Data Table

Plant Growth Data

These data are the basis for all your

later interpretations and analyses. You can

always ask new questions about the data,

but you cannot get new data without re-

peating the experiment.

Ways to Record Data

Data Tables:

- Must have a title
- Must include relevant data
- Must have labeled columns

Graphs

- After data are collected, you must determine how to display them
- One way of showing your resultsis to use a graph
- Three types of graphs are commonly used

- Pie (circle) graphs
- Line graphs
- Bar graphs

Ways to Graph Data

Pie Graph:

Used to show how a part relates to the whole

Needed to show percentages effectively

NCHS’s Biology Ice Cream Survey

Vanilla 21.0%

Chocolate 33.%

Strawberry 12.0%

Raspberry 4.0%

Peach 7.0%

Neopolitan 17.0%

Other 6.0%

Ways to Graph Data(Continued)

- Line graph: used to show change over time
- Bar graph: used to compare quantitiesin different categories
- Be sure to include:
- Title
- Axis labels
- Key

Making a Line Graph

Start with your data table

Draw and Label Axes

Experimental Data

Independent Variable on the x-axis

Average height

liquid rose (mm)

Dependent Variable on the y-axis

Submersion time (sec)

Would help to know that this experiment was done with paper towels

Making a Line Graph(Continued)

Experimental Data

Using your data table, write data pairs

(10, 11)

(15, 14)

(20, 14)

(25, 25)

(30, 16)

(35, 17)

(40, 19)

Making a Line Graph(Continued)

Use your data pairs to determine the scales for the axes

2. Write Data Pairs

(10, 11)

(15, 14)

(20, 14)

(25, 25)

(30, 16)

(35, 17)

(40, 19)

Making a Line Graph(Continued)

Start plotting your data pairs

Making a Line Graph(Continued)

After plotting data, draw a line “of best fit”

Making a Line Graph(Continued)

Complete the graph by summarizing its findings

“As the length of time the paper towel

was submerged increased, the height

the liquid rose also increased.”

Making a Bar Graph(Continued)

Using your data table, write data pairs

Making a Bar Graph(Continued)

Use your data pairs to determine the scales for the axes

Making a Bar Graph(Continued)

Start plotting your data pairs

Making a Bar Graph(Continued)

After plotting data, fill in bars

36

Include a key if needed

32

28

Water absorbed (mL)

24

20

16

C

B

E

D

F

A

Brand of paper towel

Making a Bar Graph(Continued)

5. Summarize Trends

Complete the graph by summarizing its findings

36

32

- Brands A and D were the most
- effective water absorbers.
- The least effective absorber
- was Brand B.
- Brands C, E, and F absorbed
- intermediate amounts of water.

28

Water absorbed (mL)

24

20

16

C

B

E

D

F

A

Brand of paper towel

Graphing Review

- Purposes:
- Organize and analyze data
- Show patterns
- Communicate information
- Allow scientists to make predictions

- Components:
- Appropriate title
- Equal units on each axis with good use of spacing
- Labels on each axis including units
- (example, mm, sec., kg.)

- Neatly created using a variety of color

Types of Graphs

Graph Review

Statistical Methods & Analysis of Errors

ERROR

- May be defined as a deviation from the absolute value or from the true average of a large number of results.
TYPES OF ERRORS

- Determinate error - constant
- Indeterminate error – random or accidental

Determinate Error

- Usually present in each measurement and affect all observations in a series.
- Example:
- Errors in calibration
- Operation in measuring
- Impurities in the reagents or drugs
- Biased personal errors
- Pouring or mixing
- Weighing operations
- Matching colors
- Making calculations

Indeterminate Error

- Occur by chance
- Vary from one measurement to the next
- Yield a random pattern around an average
- Occur also in the filling of capsules
- Random fluctuations in temperature and other factors

PRECISION & ACCURACY

ACCURACY – is the degree of closeness of

a measured or calculated

quantity to its actual (true)

value.

PRECISION – also called REPRODUCIBILITY

the degree to which

measurements or calculations

show the same similar results.

Prepare for an exam next meeting …

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