Chapter One: Measurement

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

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.

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.

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

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

Learn to think SI 1 cm is about the width of your little finger 1mL is about the same volume as 10 drops of water 1g is about the mass of one large paperclip 21degrees Celsius is a comfortable room temperature.

Questions pg. 8 Answer question numbers 2,6,7,8,9, 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.

REACTION TIME CHALLENGE PG. 9 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? REACTION TIME CHALLENGE PG. 9

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?

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. English vs Customary Study Jams

Remember king henry: K, H, D,( m, L,G), d, c, m A meter stick is a good tool to use for measuring ordinary lengths in the lab. A meter stick is 1 meter long and is divided into millimeters and centimeters.

Questions pg. 12 Answer questions numbers 2,4,5,7,8

1.3 Converting units Convert 655 mm to m Looking for: Given: …the distance in meters Given: …distance = 655 millimeters Relationships: Ex. There are 1000 millimeters in 1 meter Solution: 655 mm = .655 meters

Convert 142 km to m Looking for: Given: Relationships: Solution: …the distance in meters Given: …distance = 142 kilometers Relationships: Ex. There are ? meters in 1 kilometer? Solution: Use the conversion tool.

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

Metric Practice Brain pop More Metric Practice

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.

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

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

brain pop Balloon toss activity

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?

Significant Digits Digits that are always significant: Non-zero digits. Zeroes between two significant digits. All final zeroes to the right of a decimal point. Digits that are never significant: Leading zeroes to the right of a decimal point. (0.002 cm has only one significant digit.) Final zeroes in a number that does not have a decimal point. ** A decimal point is used after a whole number ending in zero to indicate that a final zero is significant. Thus 50. cm has two significant digits not one **

Practice How many significant digits does each of the following numbers have? 40 cm, 4cm, 4.0 cm, 40.cm, 45 cm, 450 cm 450.cm Convert 1.10 miles to km and report your answer with 2 significant digits. Use the relationship 1mi= 1.6 km

Answers 40cm=1 4cm=1 4.0cm=2 40.cm=2 45cm=2 450cm=2 450.=3 1.10x1.6=1.76= 1.8km

What is area of 8.5 in. x 11.0 in. paper? Looking for: Given: …area of the paper Given: … width = 8.5 in; length = 11.0 in Relationship: Area = W x L Solution: 8.5 in x 11.0 in = 93.5 in2 # Sig. fig = 94 in2

Significant Digits Pracitice

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

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”.

Error How you can you tell if two results are the same when both contain error. The estimated error is calculated by taking the group average time and subtracting each individual trial time. The estimated error is an absolute value; drop any negative signs

Is there a significant difference in data? Looking for: Significant difference between two data sets Given: Relationships: Estimate error, Average error, 3X average error Solution: The difference between the averages2.7-2.1=.6 The difference of 0.6 is six times greater that the largest estimated error(0.1) so the results are significantly different. Trial Group 1 mass (g) Est. Error Group 2 mass (g) 1 2.6 0.1 2.1 0.0 2 2.7 2.2 3 2.8 Average 0.03

Sig Diff in Meas Skill Sheet.pdf

Answer Questions pg. 23 Numbers 1,3,4,5