Chapter 2Measurement
Section 1Description and Measurement
•Every day we make observations. Sometimes those observations require that we take ______of things.
•Observations can be ______.
•Making measurements removes much of the ______about an observation.
•Measurement describes the world using ______.
-Types of measurements might include distance, time, speed, volume, and mass.
-Measurements can also help to describe ______.
However, you must choose the proper instrument when you measure something. You must consider what it measures and how precise it is.
For example: What instrument would you use to determine the winner at a swim meet? ______
How precise should that instrument be?
Description and Measurement
•Some measurements can be exact, but others are too difficult to measure exactly. In those cases we make ______measurements.
•When do you think you should make an approximate measurement?
•On what do you base that measurement?
•Approximated measurement based on previous experience is ______.
•Estimation is useful when actual measurements are ______made.
• Estimation can check that an answer is ______.
•When you estimate, you often use the word ______.
Description and Measurement
•Precision and Accuracy
–______- a description of how close measurements are to each other.
•Used to discuss a number of ______a measuring device can measure.
•Degrees of Precision – today’s measuring devices are more ______.
–______– a comparison of a measurement to the actual value.
–Precision and accuracy are important in many ______procedures.
–Measurements can be ______when precision is not needed.
•When should you not estimate a value?
•Look at the photo in Figure 3 on page 40 of your textbook. Estimate the height of the tree.
•Using Figure 4 on page 41 of your textbook, which of the three timepieces would you use to be sure to make it to school on time?
•What is the difference between precision and accuracy?
•if you don’t have the measuring instrument in front of you to determine its precision, how can you tell which numbers in the measurement are important?
•______– reflect the true precison of a calculation or measurement.
•Rules for determining significant digits:
All ______digits are significant.
Any ______between non-zero digits are significant.
Any zero to the ______of the decimal point AND to the right of a non-zero digit is significant.
How many significant digits are in each of the following numbers?
•53.275. 20.009
•6006. 93.10
•0.01237. 100.01
•8048. 54.0020
•Answers should always be recorded in a specific number of significant digits.
•In multiplication or division the measurement with the ______significant digits determines the number of significant digits in the answer.
Example: 23.056 x 21 = 484.176,
but following the above rule, the answer becomes ______.
•In addition or subtraction the number of significant digits in the answer is determined to the place value of the ______precise measurement.
Example: 23.7 + 34.65 + 83.041 =
141.391
but following the above rule, the answer becomes ______
Section 2 – SI Units
•A ______system of measurement is very important.
•In ancient times measurements were based upon the physical characteristics of the ______.
Why would this system of measurement be a problem?
•We need to be able to accurately ______measurements for science, business, and industry.
•The system that is used for this accurate communication is the ______. This system, ____, has units based upon multiples of ______.
•These units are very specific units of another system called the metric system.
(Look at Table 1 on page 46 of your textbooks.)
•The metric system is a measuring system based on multiples of ______.
•It uses a set of pre-fixes based on multiples of ten to change the meaning of the measurement.
(Look at Table 2 on page 46 of your textbooks.)
•Measuring Length
–Length is the distance between two points. In SI units it is measured in ______.
–One meter is about the length of a baseball bat or slightly longer than a yard.
•Not every length measurement should be made in meters.
The length of your pencil might be better measured in ______.
- The distance from New York to Chicago would be measured in kilometers.
•Measuring Volume
–______is the amount of space an object takes up. In SI units, volume is measured in ______.
–Just as with length, you must choose the most appropriate measurement for the object you are measuring. You would not use cubic meters to determine the volume of tea cup.
How many cubic centimeters are in a cubic meter?
–To find the volume of a regular shape – measure the length, width, and ______of the object then multiply those measurements together.
- For example: To find the volume of a wooden block, you would have to measure its length (25 cm), its width (32 cm), and its height (15 cm).
The volume is then determined by multiplying those three measurements:
25 cm x 32 cm x 15 cm =
______
–To find the volume of an irregularly shaped object you must use a method other than directly measuring the sides of the object.
The method to use in this situation is volume by ______.
This means you will place the object in a liquid (such as water) and determine how much water it ______.
That will be its volume!
•Mass
–The amount of matter in an object is its ______.
–In SI units, mass is measured in ______.
–Weight is a measurement of force.
–In SI units, weight is measured in newtons.
Weight and mass do not measure the same thing!
Mass measures how much “stuff” (______) is in an object and will not change unless we take away or add to the object.
Suppose you travel to the moon.
Will your mass change?
–Weight is determined by the pull of ______.
Your weight might change if the pull of gravity changes.
On the moon, will you weigh more, less, or the same as on Earth?
Temperature is a measure of the kinetic energy in the particles of matter.
The SI unit of temperature is the kelvin.
–Time is the interval between two events.
–The SI unit of time is the second.
______is the amount of change of one measurement in a given amount of time.
Rate can be measured in units of
Section 3Drawings, Tables, and Graphs
•______illustrations often make information more clear than written text can.
______can emphasize only necessary details or show things you can’t see.
Photographs show an object exactly as it is at a single moment.
•______display information in rows and columns for easier comprehension.
•______collect, organize, and summarize data visually.
Line graphsshows the relationship between variables, which must be numbers.
Bar graphsuse bars of different sizes to show relationships between variables; one variable is divided into parts; the other variable is a number.
Circle graphsshow parts of a whole as percentages.
Scaleson graphs must be carefully constructed and analyzed so users easily understand the information.
Don’t forget:
•Measuring is a very important part of science – it is exact and leaves no doubt in a quantity.
•In order to communicate properly, people must use a common system of measurement.
•We use drawings, tables, and graphs to communicate our ideas in forms that make the data easier to understand.
Chapter 2Measurement
The End