1. Observation, Inference, Measurements, Density and Graphing
Prologue:
Observation, Inference, Measurements, Density and Graphing

2. What are observations and inferences?
Observation – an interaction of the senses with the environment.
Instruments are used in science to enhance observations.
Examples include:
Telescope
Balance
Microscope

4. What are observations and inferences?
Inference – an interpretation of observations.
It is a hypothesis (an educated guess).

5. Determine which statements are observations and which are inferences
1. The cat has two wooden legs
2. The cat tried to eat the piranha.
3. The bird is in a cage.
4. The piranha ate the cat’s legs.
5. The bird and cat are for sale at the pet shop.

6. What is Classification?
Classification – Grouping objects and events based on observable properties.

7. Using this diagram from your Earth Science Reference Table (ESRT), how are stars classified?

8. Measurements and Instruments
Measurement – A description of observations using numbers.
Instrument – A tool that improves the ability to make observations.
Examples:
Ruler
Clock
Graduated cylinder
Triple beam balance

9. Instruments Instrument Measurement Units Ruler
Distance (between two points)
Meter (m)
Area (l x w)
Volume (l x w x h)
cm2
cm3
Graduated Cylinder
Volume
Liter (l)
ml (cm3)

10. Instruments Instrument Measurement Units Clock Time Balance Mass
Seconds
Minutes
Hours
Days
Years
Balance
Mass
Grams (g)

11. Using a Ruler cm
What is the unit of measure for this ruler (large tick marks)?
Centimeter (cm)
What is the unit for the small tick marks on the ruler?
Millimeter (mm)
How many millimeters are there between each centimeter?
10 mm are between each cm
Draw a line above the ruler from 0 to 1 cm, and draw another line from 20 to 25 mm.

12. gram (g) meter (m) liter (L)
The Metric System
In the scientific community, we use the metric system. We need to be able to convert from one unit to the other.
King (Kilo)
x 1000
Henry’s (Hecto)
x 100
Milk (milli)
x 1/1000
Daughter (Deca)
x 10
Usually (unit)
1.0
gram (g) meter (m) liter (L)
Drinks (deci)
x 1/10
Chocolate (centi)
x 1/100
To convert to a larger unit, move the decimal point to the left (or divide)
To convert to a smaller unit, move the decimal point to the right (or multiply)
The Ladder Method

13. Metric Conversions Convert the following using the Ladder Method:
3 Kg = __________ g
250 mm = ______ cm
.4 L = _________ ml
600 cm = ________ m
800 m = _______ Km
72 ml = ________ cl

14. Common Measurements in Earth Science
Mass – The amount of matter in an object.
Mass is expressed in grams (g)
Mass is measured using a balance.

15. Common Measurements in Earth Science
Mass is NOT the same thing as Weight.
Let’s compare your weight and mass on the Earth and on the Moon.
Location
Weight (Newtons N)
Mass (Kg)
Earth
120 N
12 Kg
Moon
20 N

16. Common Measurements in Earth Science
Volume – The amount of space an object takes up.
Volume is expressed in Liters (l) or cubic centimeters (cm3).
Volume is measured using a ruler or a graduated cylinder.

17. Measuring Volume - Methods
1. L x W x H
Method:
Measure length, width and height with a ruler and multiply.
Instrument used: Ruler
Units: cm3
When to use this method?
When measuring an object with a square/rectangular shape.

18. Measuring Volume - Methods
1. L x w x h
Given the values (l = 2 cm, h = 3 cm and
w = 2 cm), calculate the volume of the object.
V = l x w x h
V = 2cm x 2cm x 3 cm
V = 12 cm3

19. Measuring Volume - Methods
2. Displacement Method
Method:
Measure starting volume, place object in container and measure final volume.
Instrument used: Graduated Cylinder
Units: Liters (l)
When to use this method?
When measuring an object with an irregular shape.

20. Measuring Volume - Methods
2. Displacement Method
What is the starting
volume?
What is the ending
What is the volume
of the object?

21. Percent Error
This is the amount (in a %), by which a measurement differs from an accepted value.
Formula:
Deviation = (difference from accepted value/accepted value) x 100
This is NOT on your ESRT!!!

22. Density
Density – the concentration of matter (mass) in a space (volume).
Density is one of the most important physical properties in Earth Science.
Density is expressed in g/cm3
The formula for calculating density is:
Density = Mass/Volume (D = M/V)

23. Density Practice
What is the density of a substance that has a mass of 54.2g and a volume of 3.06cm3?
D = m/v
D = 54.2g/3.06cm3
D = 17.7g/cm3

24. Density Practice
A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of the wood?
D = m/v
D = 80g/(3cm x 6 cm x 4 cm)
D = 80g/72cm3
D = 1.1 g/cm3

25. Using Density to Solve for Mass or Volume
The formula for density looks like this…
But can also be represented like this

26. Density Practice
The density of aluminum is 2.70 g/mL. If the mass of a piece of aluminum is 244 g, what is the volume of the aluminum?

27. Density Practice
The volume of a cube is mL. If its density is g/mL, what is the mass of the cube?

28. Comparing Density Which material has a greater density? Why?
Material A
Material B
Tighter packed materials are more dense.
Looser packed materials are less dense.

29. Comparing Density A = less dense than water, it floats
B = less dense than water, more dense than A, it is under the surface.
C = has the same density as the water, it is suspended.
D = more dense than water, it sinks to the bottom.
Label each shape with the correct letter.

30. Density of a Pure Substance
If a substance or object is “uniform” or “pure” (the same throughout), the density of that object will remain the same no matter how big or small the sample.
Mass = 24g
L = 3.0 cm
W = 1.0 cm
H = 2.0 cm
Mass = 16g
L = 1.0 cm
H = 4.0 cm B A
Calculate the density of each sample of Aluminum.

31. Representing Density Density can also be represented graphically.
The density of a pure material is graphed as a straight line.
The steeper the slope of the line, the greater the density.

32. Density as a Graph Material A Point Mass(g) Volume (cm3) Density (m/v)
100
200
0.5 g/cm3 B
400 C
300
600 D
800
What is the density of ANY and EVERY point on this line?

33. Density as a Graph Material B
Use the data table to help you graph a second line. Label this line as Material B.
Material B
Point
Mass(g)
Volume
(cm3)
Density
(g/cm3) E
100
400
0.25 F
200
800 G
250
1000
What do you notice about the slope of the second line?
Compare the densities of materials A and B.

34. Density and Phases of Matter
There are three phases of matter
Solid
Liquid
Gas
The phase of matter is usually determined by how closely packed the atoms and molecules are.

35. Density and Phases of Matter
The density of a substance changes with a phase change.
Phase
Solid
Liquid
Gas
Arrangement of Atoms
Very close
Less close
Far apart

36. Density and Phases of Matter
For most Earth materials:
Density
Phase
Most Dense
Solid
Middle Density
Liquid
Least Dense
Gas
What factors can cause a phase change?
Temperature
Pressure

37. Temperature and Pressure and Density
What is the relationship between temperature and density?
As temperature increases, density decreases.
What is the relationship between pressure and density?
As pressure increases, density increases.

38. Water is the exception!!!
What happens when you place an ice cube (solid water) into a glass of water?
It floats!
Why does this happen?
Ice (solid water) is less
dense than liquid water.

39. Properties of Water Density Phase Most Dense Liquid Middle Density
Solid
Least Dense
Gas
The density of liquid water is 1.0 g/mL.
Water is densest at 3.98°C.

40. Graphing What is a graph?
A visual way to present data and how it changes. Types include; bar, pie and line graphs.

41. Types of Graphs Bar Graph Used for graphing category data
Ex: The numbers of
different m&ms in a bag.

42. Types of Graphs Pie Chart Displays parts of the whole (usually in %)
Ex: m&m colors
40% Red
35% Yellow
25% Green

43. Types of Graphs Line Graph
Shows how one variable changes with respect to another.
Independent Variable (x-axis) -the variable controlled by the scientist (I can change the independent variable).
Dependent Variable (y-axis) -the variable that changes in response to the independent variable (this is the data collected).
Uses – good for extrapolation (making predictions based on the graph’s trend).

44. Graphing Relationships
Direct Relationship
Both variables increase
Ex: as pressure increases, density increases

45. Graphing Relationships
Indirect Relationship
As one variable increases, the other decreases.
Ex: as temperature increases, density decreases.

46. Graphing Relationships
Static Relationship
As one variable increases, the other remains the same

47. Graphing Relationships
Cyclic Relationship
Shows a predictable and repeatable pattern.
Ex: Sunrise/sunset times, seasons.
Dynamic Equilibrium – a state
of balance between continuing
processes.

48. Rate of Change A measure of how fast change occurs.
Equation: ROC = Δ Value
Δ Time
Practice:
A student measures river water level and finds it has risen 10 cm in 5 hours. What is the ROC?