What is Physical Science?Chapter 1

Science The study of the natural world. To work like a scientist, you need to use

the same skills that they do.

Skills Scientists Use Observing Inferring Predicting

Observing Using one or more of your senses to

gather information Sight Sound Touch Taste smell

2 types of Observations Qualitative: a description without

numbers of measurements Quantitative: observations using

numbers or measurements Examples:

Inferring When you explain your observations Inferences are based on what you

already know. Inferences are not always correct

Predicting Making a statement about the future

What you think will happen

Physical Science The study of matter, energy, and the

changes they undergo.

Matter Anything that has mass and takes up

space Matter is all around you What isn’t matter?

Energy The ability to do work or cause a change

2 Main Branches of Physical Science Chemistry: the study of the properties

of matter and how matter changes

Physics: The study of matter, energy, motion, and forces, and how they interact

Scientific Inquiry The different ways that scientists study

the natural world. Scientific Inquiry is an ongoing process

of discovery in science.

The Process of Inquiry Scientific inquiry does not always occur

in the same way, but certain processes are involved.

Posing questions Developing hypotheses Designing experiments Collecting and interpreting data Drawing conclusions Communicating results and ideas

Posing Questions When you want to learn more about a

subject you can ask questions. Scientific questions can be answered by

making observations. Scientific questions can’t answer

questions based on opinions, values, or judgments.

Developing Hypotheses Hypothesis is a possible answer to a

scientific question. It is a prediction that can be tested. The data collected may or may not

support the hypothesis.

Developing an Experiment To test a hypothesis Determine the parameters, which are factors

that can be measured in the experiment A well designed experiment only has one

variable parameter that is intentionally changed

A controlled experiment: only one parameter is manipulated (changed) at a time.

Collecting and Interpreting Data Data Table: an organized chart for

recording observations Data are the facts, figures and evidence

collected during the experiment.

Collecting and Interpreting Data Data can be explained after it is

collected by graphing Graphing can reveal patterns in the

data

Drawing Conclusions After scientists interpret the data, they

conclude whether or not the data support the hypothesis.

Communicating The sharing of ideas and conclusions

with others through writing and speaking

Additionally, the design of the experiment is shared so that the procedures can be replicated and the results verified.

Communicating information often leads to more questions and ideas.

How Science Develops Scientists use models and develop

theories and laws to help people better understand the world.

Models A model is a graphical representation of

an object or process, like Computer models Mathematical equations Pictures 3D models

Scientific Theories A well tested explanation for a wide

range of observations or experimental results.

Theories attempt to explain “why” something happens

Theories have a large amount of supporting evidence.

Theories can be proved wrong

Scientific Laws A statement that describes an observed

pattern in nature without trying to explain it.

A scientific law is a statement that predicts what will happen every time with a given set of circumstances

Chapter 1.3 Measurement

Base Unit a unit is a standard; an agreed-on

quantity by which other quantities are measured

Always include units in your calculations and when reporting data/answers

SI: International System of units A selection of metric units that the

scientific community has agreed to use SI Units:

Time is the second (s) Length is the meter (m) Mass is the kilogram (kg) Volume is the cubic meter (m3)

But the cm3 and mL are commonly used

Volume of Rectangular Solids Length x width x height l x w x h

Volume of Irregular SolidsDetermining Volume by Water Displacement

1) Read and record the initial volume of the water in the graduated cylinder (Vi)

2) Place object in the graduated cylinder

3) Read and record the final volume of the water (Vf)

4) calculate the volume of the object (Vobj)

Vobj= Vf - Vi

Density• Density is a ratio that compares the

mass of an object to its volume. • The units for density are often grams

per cubic centimeter (g/cm3) or g/mL• Density = mass volume

Density example If a sample of a metal has a mass of 13.9 g and a

volume of 5.0 cm3, what is the density?

Density is a property that can be used to identify an unknown sample of matter. Every sample of pure aluminum has the same density.

Density Values What is the

identity of the sample in the previous problem?

Time The SI unit of time is the second (s) Longer increments of time can be

measured in minutes or hours Instruments that measure time are:

Clocks and stop watches Conversion Factors:

1 s= 1000 ms 1 min= 60 s 1 hr=60 min

Temperature Celsius and kelvin scales SI unit of Temperature is the kelvin (K) Absolute Zero (0 K): The temperature at which all motion stops. There is no lower temperature Instrument used to measure temperature:

thermometer

1.4 Math and Science Estimation: an approximation based on

known information. It is not a “guess.” Scientists use estimations when they can’t

obtain exact numbers. Accuracy: how close a measurement is

to the true or actual value. Precision or Reproducibility: how close

several measurements are to one another. Two or more measurements are needed.

ACCURACY VS. PRECISIONTarget 1

Accurate

Target 2: Not accurate but

reproducible

ACCURACY VS. PRECISIONTarget 1

Accurate and reproducible

Target 2: Not accurate nor

reproducible

Significant Figures writing numbers to reflect precision in

measurements and calculations

Significant figures in a measurement include all of the digits that have been measured exactly, plus one estimated digit.

Significant Figures

Sig Figs in CalculationsADDITION/SUBTRACTION The answer has the same number of DECIMAL

PLACES as the quantity with the fewest number of decimal places.

Example 1 Example 2

5.74 4.80.8231 - 3.965

+2.651__

Sig Figs in Calculations, cont.Multiplication/Division

The answer has the same number of sig figs as the factor with the fewest significant figures

5.02 x 89.665 x 0.10 =

5.892 / 6.10 =

Sig Figs in Calculations

Sample Problem What is the area of a ticket stub that

measures 3.50 cm by 2.2 cm? Express the answer to the correct number of significant figures.

1.5 Graphs in Science Graphs represent data as a picture They can reveal trends that you may not

see from a data table

Line Graphs Show the relationship

between variables Show how the

responding variable changes in response to the manipulated variable

Plotting a Line Graph1) Draw and label the axes.

a) x axis: manipulated variableb) y axis: responding variable

2) Determine the scale…the spaces are of equal interval

3) Plot the data from the data table4) Draw a line of best fit

a. A line that goes through the most points. Do not “connect the dots.”

5) Add a title: the title states the relationship between the variables or ID’s the variables

A graph that yields a straight line is called a LINEAR GRAPH

Why a “Line of Best Fit?” Errors in measurement occur, so not all

the points will fall exactly on a straight line

By connecting the points, too much importance is placed on the individual points rather than on the general trend.

A “Line of Best Fit” emphasizes the overall trend shown by the data

Slope Tells the change in y for every change in x

Slope = rise = y2-y1

run x2- x1

To determine the slope: choose any 2 points on the line plug them into the slope formula Calculate and include the units. This slope

value is a constant. y= kx can be used to calculate for an

unknown value of y or x (k is the slope).