Pearson Prentice Hall Physical Science: Concepts in Action Chapter 1 Science Skills

1.1 What is Science? Objectives 1. Describe how the process of science starts and ends. 2. Explain the relationship between science and technology. 3. Describe the main branches of natural science and relate them to each other.

Science involves asking questions about nature and then finding ways to answer them These questions arise from the natural curiosity of human beings Definition: science is a system of knowledge and the methods you use to find that knowledge

How the Process Starts & Ends + Technology Science begins with curiosity and often ends with discovery Definition: technology is the use of knowledge to solve practical problems Science and technology depend on each other- advances in one lead to advances in the other

Branches Natural science is divided into 3 branches: physical science, Earth & space sci, and life sci Phys sci has 2 main branches: chemistry & physics Definition: chemistry is the study of composition, structure, properties & reactions of matter Definition: physics is the study of matter & energy, and the interactions between the two through forces & motion

Chemistry & physics are applied to study the Earth The foundation of earth sci is geology Definition: geology is the study of the origin, history & structure of Earth Geology focuses Earth’s rocks

Astronomy is the foundation of space sci Definition: astronomy is the study of the universe beyond Earth It includes the sun, moon & stars Our study of physical science will include chemistry, physics, Earth and space sciences

Life science is the 3 rd branch of natural science It is also called biology Definition: biology is the study of living things We will not focus on biology in this class although certain aspects of it may come up from time to time This class will focus on matter & change, space & time, forces, motion & energy

1.2 Using a Scientific Approach Objectives: 1. Explain the goal of the scientific method 2. Define how scientific law differs from scientific theory 3. Explain why scientific models are useful 4. Analyze why it is important to follow instructions and directions exactly in science.

Goal of the Method Definition: scientific method is an organized plan for gathering, organizing and communicating information The goal of any sci method is to solve a problem or to better understand an observed event

There are several steps to using the sci method: 1. make an observation- definition: an observation is information you obtain through your senses 2. ask a question from the observation 3. develop a hypothesis- definition: a hypothesis is a proposed answer to the question based on an educated guess

A. the hypothesis must be testable in order to be useful 4. test the hypothesis by performing an experiment A. definition- a controlled experiment is an experiment where only one variable (the manipulated variable) is changed at a time B. definition: a variable is a piece of data or a condition that can change

C. definition: a manipulated variable is a condition (temp, speed, etc.) that causes a change in another condition D. definition: responding variable is the variable that changed 5. collect (and record) data on the responding variable 6. analyze the data usually with graphs, charts or mathematical interpretations

7. draw conclusions from the analysis A. if the hypothesis is not supported (notice you do not say the hypothesis is “wrong”!), revise the hypothesis and do a different experiment to test the new hypothesis B. If the hypothesis is supported (the hypothesis is not “right” or “correct”, it is supported), develop a theory

Scientific Theory 8. develop a theory- definition: a scientific theory is a well tested explanation for a set of observations or experimental results A. a theory is not possible for just one experiment- the results must be reproducible by you and many other scientists B. theories are never proved, but become stronger if facts continue to support them & revised or dropped if new facts & discoveries occur

Scientific Law Definition: scientific law is a statement that summarizes a pattern found in nature It occurs after repeated observations or experiments A sci law does not explain an observed pattern in nature A sci law only describes the pattern The explanation of the pattern comes from sci theory

Following Directions Definition: a model is a representation of an object or event A scientific model makes it easier to understand thing that might be difficult to observe directly Safety is very important in science Scientists use “STANDARD PRECATIONS” when working with difficult or dangerous materials ALWAYS FOLLOW DIRECTIONS AND INSTRUCTIONS EXACTLY WHEN PERFORMING ANY SCIENTIFIC ANALYSIS

1.3 Measurement Objectives: 1. Analyze why scientific notation is useful 2. Define the units that scientists use for their measurements 3. Explain precision and accuracy

Usefulness of Sci Notation Scientific notation expresses a value by using a number between 1 & 10 (the coefficient), & a power of 10 Sci notation makes very large or very small numbers easier to work with

Practice with Scientific notation 1. write the number 3,000,000 in scientific notation A: 3 x write the number in scientific notation A: 6 x 10 -5

When dividing numbers written in sci notation, divide the coefficients and subtract the exponents 4. Calculate how far light travels in 8.65 x 10 4 seconds if the speed of light is 3.0 x 10 8 m/s A: The problem asks how FAR, so the answer is in METERS A: 8.65/ 3.0 = /10 8 = 10 -4, So 2.88 x 10 -4

When multiplying numbers in sci notation, multiply the coefficients and add exponents 3. Perform the calculation. Express your answer in sci notation: (7.6 x m) x (1.5 x 10 7 m) A: 7.6 x 1.5 = x 10 7 = x 10 3 = 1.14 x 10 4

Units & Conversions You will also learn how to use the exponent function on your calculator in this class SI units are the international system of units used by scientists to measure Seven metric units are the base units given in tables that follow- you must know these You must also know the metric prefixes that describe how large the numbers are

Definition: a conversion factor is a ratio of equivalent measurements that converts a quantity expressed in one unit to another unit Problem: Express 8848 meters in kilometers A: 1 kilometer = 1000 meters, so they are a ratio: 1 km/1000m OR 1000m/1km

Since the ratio are numbers that are equal to each other, it is a way to express the number 1 You may use the mathematical trick of cross cancellation in deciding which ratio to use A:8848m x 1 km/1000m =8.848km To convert back to meters, use this setup: 8.848km x 1000m/1km=8848m In this setup the km cancels

Density Density is an object’s mass divided by its volume Density = mass/volume The units for mass are usually grams The units for volume are either cm 3 or mL Notice that neither measurement is a base unit, but a combination of derived and SI prefixes

Let’s practice density: The mass of a piece of iron is g. The volumes is 4.42 cubic centimeters. What is its density? A:34.73g/4.42cm 3 = 7.85 g/cm 3 Try this one: The density of an object is 4.32 g/cm 3. If the mass of the object is 8.64 g, what is the volume?

What are you looking for? A: volume What units will your answer have? A: cm 3 The density is expressed as a volume and can be thought of as a conversion factor, so it can be expressed as either 4.32 g/cm 3 or 1cm 3 /4.32g You need to cross cancel, so which ratio will you use to set up your problem where you must find cm 3 ?

A: Use 1cm 3 /4.32g and set up the problem this way: 8.64 g x 1cm 3 /4.32g = 2 cm 3 Notice that when you set up the problem this way, the grams will cross cancel and you will be able to find the volume (which is cm 3 ) Special note: 1 mL = 1 cm 3, so these units can be used interchangeably If you have a liquid, you should use mL for the volume to express density

Precision, Accuracy, Sig Figs & Temperature Measurement Precision is how exact a measurement is This means that if you tested the object 5 times, you would get close to the same answer 5 times Accuracy is how close to the true measurement the result is

The precision of a calculated answer is limited by the least precise calculation The least precise calculation has the fewest significant figures

Significant Figures Significant figures are some-times called sig figs (slang) Significant figures are all the digits that are known in a measurement, plus the last digit is estimated 5.25 min has 3 sig figs, 5 min has 1 sig fig and so on Answers to calculations should only have the same number of figures as the least precise measurement

For example: density = 34.73g/4.42cm 3 = g/cm 3 The answer should only have 3 significant figures because the volume (4.42 cm 3 ) has 3 sig figs In this case, the volume is the least precise measurement and the answer should be rounded to 7.86 g/cm 3

Temperature Conversions Definition: thermometer- instrument that measures temperature or how hot an object is There are 3 temperature scales to convert back and forth from

The scales are Fahrenheit, Celsius (also called centigrade) & Kelvin More on the temperature scales later, but for now, here are the conversions:

Practice a temperature conversion: Convert -11ºF into degrees Celsius and then into kelvins (notice that you do not use “degrees” with the Kelvin scale) A: first go from ºF to ºC (-11 – 32)= x 5/9= -24ºC -24ºC = 249 K

1.4 Presenting Scientific Data Objectives: 1. Explain how scientists organize data 2. Explain how scientists communicate experimental data.

Scientists use data tables and graphs Data tables can list all sorts of observations Line graphs are also used The steepness of the line is called the slope Slope = rise/run

Scientists have a variety of ways they communicate with each other They can … write in scientific journals Speak at conferences one another Produce websites Converse

Definition: a direct proportion is a relationship in which the ratio (division) between 2 variables is constant Definition: an inverse proportion is the relationship in which the product (multiplication) between 2 variables is constant Bar graphs compare sets of measurements Circle graphs or pie charts show how a part of something relates to the whole usually as a percentage