1. Science From Curiosity
How does the process of science start and end?

2. Science From Curiosity
Science begins with curiosity and often ends with discovery.

3. Science From Curiosity
Curiosity provides questions, but scientific results rely on finding answers.
In some experiments, observations are qualitative, or _____________.
In other experiments, observations are quantitative, or _____________.
Some questions—for example, how the universe began—cannot be answered by direct observations and measurements but only by other kinds of evidence.

4. Science and Technology
What is the relationship between science and technology?
Science and technology are interdependent. Advances in one lead to advances in the other.

5. Science and Technology

6. The telephone was invented in 1876
The telephone was invented in By 1927, it was possible to make a phone call from New York to London. The first mobile telephones, invented during World War II, paved the way for modern cellular phones. At each step, new science was applied to improve the technology of the telephone.

7. Branches of Science
What are the branches of natural science?

8. Branches of Science
Natural science is generally divided into three branches: physical science, Earth and space science, and life science.

9. Physical science focuses on nonliving things.
Chemistry is the study of the composition, structure, properties, and reactions of matter.
Physics is the study of matter and energy and the interactions between the two through forces and motion.

10. The application of physics and chemistry to the study of Earth is called Earth science.
Geology is the study of the origin, history, structure, and systems of Earth.
Astronomy is the study of the universe beyond Earth.

11. The study of living things is known as biology, or life science.
Biology includes the physics and chemistry of living things, as well as their origin and behavior.
Biologists study the different ways that organisms grow, survive, and reproduce.

12. There is overlap between different areas of science.
Much of biology involves changes that are part of chemistry, while much of chemistry is defined by interactions that are part of physics
Biophysics is a growing area of physics that applies physics to biology.

13. The Big Ideas of Physical Science
Space and Time
The universe is both very old and very big.
Matter and Change
A very small amount of the universe is matter. All matter that you are familiar with is made up of building blocks called atoms.

14. The Big Ideas of Physical Science
Forces and Motion
Forces cause changes in motion. The laws of physics allow these changes to be calculated exactly.
Energy
Energy exists in many forms. Energy can be transferred from one form or object to another, but it can never be destroyed.

15. You are caught in the rain. Should you run or walk
You are caught in the rain. Should you run or walk? Maybe you should run–less time in the rain means less water falls down on you. Maybe you should walk–moving slower causes you to run into fewer drops. This is a question that you can try to answer with a scientific approach.

16. Scientific Methods
What is the goal of a scientific method?

17. Scientific Methods
An organized plan for gathering, organizing, and communicating information is called a scientific method.
You can use a scientific method to search for the answer to a question.
Scientific methods can vary from case to case, depending on the question and how the researcher decides to look for an answer.

18. Scientific Methods
The goal of any scientific method is to solve a problem or to better understand an observed event.

19. Scientific Methods
Here is an example of a scientific method. Each step uses specific skills. The order of steps can vary. Sometimes you will use all of the steps and other times only some of them.

20. Scientific Methods
Making Observations
Scientific investigations often begin with observations. An observation is
Forming a Hypothesis
A hypothesis is

21. In an experiment, any factor that can change is called a variable.
Scientific Methods
Testing a Hypothesis
In an experiment, any factor that can change is called a variable.
The manipulated variable causes a change.
The responding variable changes in response to the manipulated variable.
A controlled experiment is an experiment in which only one variable, the manipulated variable, is deliberately changed at a time.

22. Scientific Methods
Drawing Conclusions
A conclusion describes how facts apply to a hypothesis.
Developing a Theory
A scientific theory is ______________________
_______________________. Once a hypothesis has been supported in repeated experiments, scientists can begin to develop a theory.

23. Scientific Methods
Question: How does speed affect how wet you get in the rain?
Hypothesis: The faster your speed, the drier you will stay.
Experiment: Test whether speed affects how wet you get in the rain.

24. Scientific Methods
In 1997, two meteorologists conducted a controlled experiment to determine if moving faster keeps you drier in the rain.
One scientist walked 100 yards and the other ran the same distance. Variables, such as type of clothes, were controlled.

25. Scientific Methods
The clothes of the walking scientist accumulated 217 grams of water; the clothes of the running scientist accumulated 130 grams of water.
Draw a Conclusion: The scientists concluded that running in the rain keeps you drier.

26. Scientific Laws
How does a scientific law differ from a scientific theory?

27. Scientific Laws
After repeated observations or experiments, scientists may arrive at a scientific law.
A scientific law
For example, Newton’s law of gravity is a scientific law that has been verified over and over. Scientists have yet to agree on a theory that explains how gravity works.

28. Scientific Laws
A scientific law describes an observed pattern in nature without attempting to explain it. The explanation of such a pattern is provided by a scientific theory.

29. Scientific Models
Why are scientific models useful?
A model is __________________________
_________. A street map is a model of a city.
Scientific models make it easier to understand things that might be too difficult to observe directly.

30. Scientific Models
This computer model represents the interior of an airplane. It helps the engineers visualize the layout of the plane.

31. Scientific Models
Models help you visualize things that are too small to see, such as atoms, or things that are large, such as the solar system.
An example of a mental, rather than physical, model might be that comets are like giant snowballs, primarily made of ice.
As new data are collected, models can be changed or be replaced by new models.

32. Working Safely in Science
Safety plays an important role in science. Laboratory work may involve flames or hot plates, electricity, chemicals, hot liquids, sharp instruments, and breakable glassware.
Always follow your teacher’s instructions and the textbook directions exactly.

33. How old are you. How tall are you
How old are you? How tall are you? The answers to these questions are measurements. Measurements are important in both science and everyday life. It would be difficult to imagine doing science without any measurements.

34. Using Scientific Notation
Why is scientific notation useful?

35. Using Scientific Notation
Why is scientific notation useful?
Scientists often work with very large or very small numbers. Astronomers estimate there are 200,000,000,000 stars in our galaxy.

36. Using Scientific Notation
Scientific notation is a way of expressing a value as the product of a number between 1 and 10 and a power of 10.
For example, the speed of light is about 300,000,000 meters per second. In scientific notation, that speed is 3.0 × 108 m/s. The exponent, 8, tells you that the decimal point is really 8 places to the right of the 3.

37. Using Scientific Notation
For numbers less than 1 that are written in scientific notation, the exponent is negative.
For example, an average snail’s pace is meters per second. In scientific notation, that speed is 8.6 × 10-4 m/s. The negative exponent tells you how many decimals places there are to the left of the 8.6.

38. Using Scientific Notation
To multiply numbers written in scientific notation, you multiply the numbers that appear before the multiplication signs and add the exponents. The following example demonstrates how to calculate the distance light travels in 500 seconds.
This is about the distance between the sun and Earth.

39. Using Scientific Notation
When dividing numbers written in scientific notation, you divide the numbers that appear before the exponential terms and subtract the exponents. The following example demonstrates how to calculate the time it takes light from the sun to reach Earth.

40. Using Scientific Notation
A rectangular parking lot has a length of 1.1 × 103 meters and a width of 2.4 × 103 meters. What is the area of the parking lot?

41. Using Scientific Notation
Look Back and Check
1. Perform the following calculations. Express your answers in scientific notation.
a. (7.6 × 10-4 m) × (1.5 × 107 m)
b ÷ 29
2. Calculate how far light travels in 8.64 × 104 seconds. (Hint: The speed of light is about 3.0 × 108 m/s.)

42. SI Units of Measurement
What units do scientists use for their measurements?

43. SI Units of Measurement
Scientists use a set of measuring units called SI, or the International System of Units.
SI is an abbreviation for Système International d’Unités.
SI is a revised version of the metric system, originally developed in France in 1791.
Scientists around the world use the same system of measurements so that they can readily interpret one another’s measurements.

44. SI Units of Measurement
If you told one of your friends that you had finished an assignment “in five,” it could mean five minutes or five hours. Always express measurements in numbers and units so that their meaning is clear.
These students’ temperature measurement will include a number and the unit, °C.

45. SI Units of Measurement
Base Units and Derived Units
SI is built upon seven metric units, known as base units.
In SI, the base unit for length, or the straight-line distance between two points, is the __________.
The base unit for mass, or the quantity of matter in an object or sample, is the _____________.

46. SI Units of Measurement
Seven metric base units make up the foundation of SI.

47. SI Units of Measurement
Additional SI units, called derived units, are made from combinations of base units.
Volume is the amount of space taken up by an object.
Density is the ratio of an object’s mass to its volume:

48. SI Units of Measurement
Specific combinations of SI base units yield derived units.

49. SI Units of Measurement
To derive the SI unit for density, you can divide the base unit for mass by the derived unit for volume. Dividing kilograms by cubic meters yields the SI unit for density, kilograms per cubic meter (kg/m3).
A bar of gold has more mass per unit volume than a feather, so gold has a greater density than a feather.

50. SI Units of Measurement
Metric Prefixes
The metric unit is not always a convenient one to use. A metric prefix indicates how many times a unit should be multiplied or divided by 10.

51. SI Units of Measurement
For example, the time it takes for a computer hard drive to read or write data is in the range of thousandths of a second, such as second. Using the prefix milli- (m), you can write second as 9 milliseconds, or 9 ms.

52. SI Units of Measurement
Metric prefixes can also make a unit larger. For example, a distance of 12,000 meters can also be written as 12 kilometers.
Metric prefixes turn up in nonmetric units as well. If you work with computers, you probably know that a gigabyte of data refers to 1,000,000,000 bytes. A megapixel is 1,000,000 pixels.

53. SI Units of Measurement
A conversion factor is a ratio of equivalent measurements used to convert a quantity expressed in one unit to another unit.
To convert the height of Mount Everest, 8848 meters, into kilometers, multiply by the conversion factor on the left.

54. SI Units of Measurement
To convert kilometers back into meters, multiply by the conversion factor on the right. Since you are converting from kilometers to meters, the number should get larger.
In this case, the kilometer units cancel, leaving you with meters.

55. Limits of Measurement
How does the precision of measurements affect the precision of scientific calculations?

56. Limits of Measurement
Precision
Precision is a gauge of how exact a measurement is.
Significant figures are all the digits that are known in a measurement, plus the last digit that is estimated.

57. Limits of Measurement
The precision of a calculated answer is limited by the least precise measurement used in the calculation.

58. Limits of Measurement
A more precise time can be read from the digital clock than can be read from the analog clock. The digital clock is precise to the nearest second, while the analog clock is precise to the nearest minute.

59. Limits of Measurement
If the least precise measurement in a calculation has three significant figures, then the calculated answer can have at most three significant figures.
Mass = grams
Volume = 4.42 cubic centimeters.
Rounding to three significant figures, the density is 7.86 grams per cubic centimeter.

60. Limits of Measurement
Accuracy
Another important quality in a measurement is its accuracy. Accuracy is the closeness of a measurement to the actual value of what is being measured.
For example, suppose a digital clock is running 15 minutes slow. Although the clock would remain precise to the nearest second, the time displayed would not be accurate.

61. Measuring Temperature
A thermometer is an instrument that measures temperature, or how hot an object is.

62. Measuring Temperature
Scale The scale indicates the
temperature according to how
far up or down the capillary
tube the liquid has moved.
Celsius (centigrade)
temperature scale
Fahrenheit scale
Capillary tube
Colored liquid The liquid moves up and down the capillary tube as the temperature changes.
Bulb The bulb
contains the
reservoir of liquid.

63. Measuring Temperature
Compressed
scale
Liquid rises
more in a
narrow tube
for the same
temperature
change.
Liquid rises
less in a
wide tube
for the same
temperature
change.
Expanded,
easy-to-read scale

64. Measuring Temperature
The two temperature scales that you are probably most familiar with are the Fahrenheit scale and the Celsius scale.
A degree Celsius is almost twice as large as a degree Fahrenheit.
You can convert from one scale to the other by using one of the following formulas.

65. Measuring Temperature
The SI base unit for temperature is the kelvin (K).
A temperature of 0 K, or 0 kelvin, refers to the lowest possible temperature that can be reached.
In degrees Celsius, this temperature is –273.15°C. To convert between kelvins and degrees Celsius, use the formula:

66. Measuring Temperature
Temperatures can be expressed in degrees Fahrenheit, degrees Celsius, or kelvins.

67. In order for news to be useful, it must be reported in a clear, organized manner. Like the news, scientific data become meaningful only when they are organized and communicated. Communication includes visual presentations, such as this graph.

68. Organizing Data
How do scientists organize data?

69. Organizing Data
Scientists can organize their data by using data tables and graphs.

70. Organizing Data Data Tables
The simplest way to organize data is to present them in a table. This table relates two variables—a manipulated variable (location) and a responding variable (average annual precipitation).

71. Organizing Data
Line Graphs
A line graph is useful for showing changes that occur in related variables.
In a line graph, the manipulated variable is generally plotted on the horizontal axis, or x-axis.
The responding variable is plotted on the vertical axis, or y-axis, of the graph.

72. Sometimes the data points in a graph yield a straight line.
Organizing Data
Sometimes the data points in a graph yield a straight line.
The steepness, or slope, of this line is the ratio of a vertical change to the corresponding horizontal change.
The formula for the slope of the line is

73. Organizing Data
Plotting the mass of water against the volume of water yields a straight line.

74. Organizing Data
A direct proportion is a relationship in which the ratio of two variables is constant. The relationship between the mass and the volume of water is an example of a direct proportion.
A 3-cubic-centimeter sample of water has a mass of 3 grams.
A 6-cubic-centimeter sample of water has a mass of 6 grams.
A 9-cubic-centimeter sample of water has a mass of 9 grams.

75. Organizing Data
This graph shows how the flow rate of a water faucet affects the time required to fill a 1-gallon pot.

76. Organizing Data
An inverse proportion is a relationship in which the product of two variables is a constant.
A flow rate of 0.5 gallon per minute will fill the pot in 2 minutes.
A flow rate of 1 gallon per minute will fill the pot in 1 minute.
A flow rate of 2 gallons per minute will fill the pot in 0.5 minute.

77. Organizing Data Faster Than Speeding Data
A modem is a device used to send and receive data. For example, if you upload an image to a Web site, the modem in your computer converts the data of the image into a different format. The converted data are then sent through a telephone line or cable TV line. The smallest unit of data that can be read by a computer is a binary digit, or “bit.” A bit is either a 0 or a 1. Computers process bits in larger units called bytes. A byte is a group of eight bits.

78. Organizing Data
The table shows the data transfer rates for modems used in home computers. Data transfer rates are often measured in kilobits per second, or kbps. The time required to upload a 1-megabyte (MB) file is given for each rate listed.

79. Organizing Data
Using Graphs Use the data in the table to create a line graph. Describe the relationship between data transfer rate and upload time.
Answer:

80. Organizing Data
2. Inferring How would doubling the data transfer rate affect the upload time?
Answer: Doubling the data transfer rate would halve the upload time.

81. Organizing Data
Bar Graphs
A bar graph is often used to compare a set of measurements, amounts, or changes.

82. Organizing Data Circle Graphs
If you think of a pie cut into pieces, you have a mental model of a circle graph. A circle graph shows how a part or share of something relates to the whole.

83. Communicating Data
How can scientists communicate experimental data?

84. Communicating Data
Scientists can communicate results by writing in scientific journals or speaking at conferences.

85. Communicating Data
Scientists also exchange information through conversations, s, and Web sites. Young scientists often present their research at science fairs.

86. Communicating Data
Peer review is a process in which scientists examine other scientists’ work.
Peer review encourages comments, suggestions, questions, and criticism from other scientists.
Based on their peers’ responses, the scientists who submitted their work for review can then reevaluate how to best interpret their data.