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

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

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

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.

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

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

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

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)

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

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.

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

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

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.

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

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.

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.

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

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.

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

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!!!

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)

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

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

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

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?

Density Practice The volume of a cube is 195.1 mL. If its density is 0.917 g/mL, what is the mass of the cube?

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.

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.

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.

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.

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?

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.

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.

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

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

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.

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.

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.

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

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

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

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).

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

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

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

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

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?