Chapter 1 Review Problems (Done in Class)

Transcription

1 Chapter 1 Measurement Review Problems Chapter 1 Review Problems (Done in Class) Section - problems Sec 1, p. 8 # 2, 5, 6, 8, 9 Sec 2, p. 12 # 1, 3, 4, 5, 7, 8 Sec 3, p.17 # 3, 4, 5 Sec 4, p. 23 # 3, 6, 7

2 Chapter One: Measurement 1.1 Measurements 1.2 Time and Distance 1.3 Converting Measurements 1.4 Working with Measurements

3 1.1 Measurements A measurement is a determination of the amount of something. A measurement has two parts: a number value and a unit

4 1.1 Two common systems The English System is used for everyday measurements in the United States. Miles, yards, feet, inches, pounds, pints, quarts, gallons, cups, and teaspoons are all English system units. In 1960, the Metric System was revised and simplified, and a new name was adopted International System of Units.

5 1.1 International System of Measurement (SI) The acronym SI comes from the French name Le Système International d Unités. SI units form a base-10 or decimal system. In the metric system, there are: 10 millimeters in a centimeter, 100 centimeters in a meter, and 1,000 meters in a kilometer.

6 1.1 The meter stick A meter stick is 1 meter long and is divided into millimeters and centimeters.

7 1.1 The meter stick Each centimeter is divided into ten smaller units, called millimeters. What is the length in cm?

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9 Chapter One: Measurement 1.1 Measurements 1.2 Time and Distance 1.3 Converting Measurements 1.4 Working with Measurements

10 1.2 Time and Distance Two ways to think about time: What time is it? How much time? A quantity of time is also called a time interval.

11 1.2 Time Time comes in mixed units. Seconds are very short. For calculations, you may need to convert hours and minutes into seconds. How many seconds is this time interval?

12 1.2 Distance Distance is the amount of space between two points. Distance is measured in units of length. The meter is a basic SI distance unit. In 1791, a meter was defined as one ten-millionth of the distance from the North Pole to the equator. What standard is used today?

13 1.2 Metric prefixes Prefixes are added to the names of basic SI units such as meter, liter and gram. Prefixes describe very small or large measurements.

14 DIN 1. When you are doing a measurement lab, your friend says he is five feet 10 inches tall. How tall are you in meters? (Note: 1 cm = inches) 2. You are on the Robert E. Lee HS Marathon High team and run the half marathon in 3 hours, 22 minutes. How many seconds did it take you to run the race?

15 1.3 Converting units To convert 1,565 pennies to the dollar amount, you divide 1,565 by 100 (since there are 100 pennies in a dollar). Converting SI units is just as easy as converting pennies to dollars.

16 Solving Problems Convert 655 mm to m 1. Looking for: the distance in meters 2. Given: distance = 655 millimeters 3. Relationships: Ex. There are 1000 millimeters in 1 meter 4. Solution: 655 mm =.655 meters

17 Solving Problems Convert 142 km to m 1. Looking for: the distance in meters 2. Given: distance = 142 kilometers 3. Relationships: Ex. There are? meters in 1 kilometer? 4. Solution: Use the conversion tool.

18 Solving Problems Convert 754,000 cm to km 1. Looking for: the distance in kilometers 2. Given: distance = 754,000 centimeters 3. Relationships: Ex. There are? cm in 1 m? There are? m in 1 km? 4. Solution: Use the conversion tool.

19 Chapter One: Measurement 1.1 Measurements 1.2 Time and Distance 1.3 Converting Measurements 1.4 Working with Measurements

20 1.4 Working with Measurements Accuracy is how close a measurement is to the accepted, true value. Precision describes how close together repeated measurements or events are to one another.

21 1.4 Working with Measurements In the real world it is impossible for everyone to arrive at the exact same true measurement as everyone else. Find the length of the object in centimeters. How many digits does your answer have?

22 1.4 Working with Measurements Using the bow and arrow analogy explain how it is possible to be precise but inaccurate with a stopwatch, ruler or other tool.

23 1.4 Resolution Resolution refers to the smallest interval that can be measured. You can think of resolution as the sharpness of a measurement.

24 1.4 Working with Measurements Digits that are always significant: 1. Non-zero digits. 2. Zeroes between two significant digits. 3. All final zeroes to the right of a decimal point. Digits that are never significant: 4. Leading zeroes to the right of a decimal point. (0.002 cm has only one significant digit.) 5. Final zeroes in a number that does not have a decimal point.

25 Solving Problems What is area of 8.5 in. x 11.0 in. paper? 1. Looking for: area of the paper 2. Given: width = 8.5 in; length = 11.0 in 3. Relationship: Area = W x L 4. Solution: 8.5 in x 11.0 in = 93.5 in 2 # Sig. fig = 94 in 2

26 1.4 Significant differences In everyday conversation, same means two numbers that are the same exactly, like 2.56 and When comparing scientific results same means not significantly different. Significant differences are differences that are MUCH larger than the estimated error in the results.

27 1.4 Error and significance How can you tell if two results are the same when both contain error (uncertainty)? When we estimate error in a data set, we will assume the average is the exact value. If the difference in the averages is at least three times larger than the average error, we say the difference is significant.

28 1.4 Error How you can you tell if two results are the same when both contain error. Calculate error Average error Compare average error

29 Solving Problems Is there a significant difference in data? 1. Looking for: Significant difference between two data sets 2. Given: Table of data 3. Relationships: Estimate error, Average error, 3X average error 4. Solution: Ø Math answer: 93.5 in 2 Ø Determine # of significant figures = 94 in 2