1. Chapter 2
Measurement

2. Description and
Measurement
2.1

3. A. Measurement A way to describe the world with numbers
Answers questions such as how much, how long, or how far
Can describe cost ($), distance, volume, mass, speed
In scientific endeavors, scientists rely on measurements instead of opinions
Why is it important for doctors to know how much the heart pumps blood?

4. When would it be important to measure an amount of air?
Air available inside of an airplane
Air inside of a firefighter’s airpac
Air inside of a rocket ship for astronauts

5. Why is it important for certain events, like swimming to be measured?
Events can be measured
Why is it important for certain events, like swimming to be measured?
2008 Summer Olympics, Michael Phelps swam the 100m butterfly and won his 7th gold medal for a singles event by a hundredth of a second
Michael Phelps – 50.57
Milorad Cavic –

6. B. Estimation To give a rough measurement of an object
Usually used when you don’t have the right tool to make an exact measurement
Can use your knowledge of the size of something familiar to estimate the size of a new object
A skill based on previous experience and is useful when you are in a hurry and exact numbers are not required
A valuable skill that improves with experience, practice, and understanding

7. When do you estimate? Come up with one on your own.
How much bread a restaurant warms up for the different tables coming in.
How many papers to print off for a meeting.
How much money you need for a trip.
How much ingredients to put in a recipe.
How much dog food to put in the bowl.

8. c. 1. Precision
One way to evaluate measurements is to determine whether they are precise
Precise – a description of how close measurements are to each other
Precision is used when discussing the number of decimal places a measuring device can measure
A wall clock or a clock with a second hand
Making a measurement and getting the same result each time or your friend measuring the same thing and getting different answers each time

9. c. 2. Accuracy
When you compare a measurement to the real, actual, or accepted value
The second hand on a watch will give a precise time (7:38:10 p.m.) but it’s not accurate if it is 25 minutes behind
“But officer, my speedometer says I’m only going 40?!”

10. c.3. Rounding a measurement
Not all measurements require an exact measurement
Rounding rules
Look at the number to the right of the place you are rounding
If it is 0-4, it stays the same
If it is 5-9, it goes up one
The length of the walk to school.
You could measure it to nearest millimeter
But only would need to know to the nearest meter or tenth of a meter and still be accurate such as 2,348.50

11. c. 4. precision and number of digits
Let’s say you have a bag of M&M’s and you want to share it with your friends.
There are 4 of you and 30 M&M’s…
Each of you will get 7 M&M’s but there are 2 left over?
Would you bother to cut the 2 M&M’s in half so everyone gets exactly the same amount or would someone just eat the 2 extra M&M’s?

12. c.5. Using precision and Significant digits
Significant digits or figures – the number of digits that truly reflect the precision of a number
Digits other than zero are always significant
Final zeros after a decimal point ( g) are significant
Zeros between any other digits ( g) are significant
Zeros before any other digits ( g) are NOT significant
Zeros in a whole number (1650) may or may not be significant
An exact number, such as the number of people in a room or the number of meters in a kilometer, has infinite significant digits

13. C.6. Following the rules
Multiplication and division, you determine the number of significant digits in each number in your problem
6.14 x 5.6 =
3 digits digits 2 digits
For addition and subtraction, you determine
the place value of each number in your problem
to the hundredths
to the tenths
to the tenths

14. 2.2
SI Units

15. A. The international system
It would be awfully confusing if every country in the world had a different system of measurement.
In 1960, scientists established the International
System of Units (SI) as the accepted system for
measurement
Designed for a worldwide standard of physical
measurement for science, industry and commerce

16. Si base units

18. b. length The distance between two points
Depending on the tool depends on what you are measuring and depending on what you are measuring depends on what you are measuring!
Meter – the SI unit of length
one meter is about the length of a baseball bat
1 meter = feet
Size of a room or a building would be measured in meters

19. Smaller objects can be measured in centimeters (cm) or millimeters (mm)
Textbook or pencil could be measured in cm
Twenty dollar bill is 15.5 cm long
Mm could be used to measure the letters in your text book
Scientist use micrometers and nanometers to measure
really small things such as blood cells, bacteria or viruses

20. b.1. a long way
Long distances are measured with kilometers such as distance from the earth to the moon or how long a bird flies
Kilometers are also used for distance in a car or length of a long race
OBJECT
TYPE OF MEASUREMENT
MEASUREMENT
Can of soda
Volume
355 cm to 3rd power
Bag of potatoes
Mass
4.5 kg
Fluorescent tube
Length
1.2 m
Refrigerator
Temperature
276 K

21. c. volume the amount of space an object occupies
You can measure smaller volumes with cubic centimeters
To find the volume of an object, measure its length, width, and height and multiply them

22. Liter – a measurement of liquid volume
Ex. a 2-L water bottle

23. c.1. volume by immersion
To find the volume of something that is irregularly shaped, you can simply add it to water
If you add ice cubes to a full glass of water, the water that spills over is displaced due to the addition of the volume of ice
The volume of the water was not increased, but the volume of the ice displaced the water
The difference in the volume of the ice cubes that are under the surface of the water
Ice cubes took up space and caused the total volume in the glass to increase

24. Add the irregular shaped item to a glass of water, but you must start with knowing the volume of the water first
The increase of volume of water is equal to the volume of the object

25. d. mass Mass – the amount of matter in an object
Kilogram – (kg) SI unit for mass
One liter of water has a mass of 1 kg
Smaller masses are measured in grams (g)
One gram is the size of a large paper clip
A triple beam balance can determine mass

26. Weight and mass are not the same.
Mass depends only on the amount of matter in an object
Mass won’t change when only your location changes
Elevators and space shuttles

27. d.1. weight Measurement of force SI unit is newton (N)
Depends on gravity which can change depending on where the object is located
Spring scale is used to measure how a planet’s gravitational force pulls on objects

28. Your weight would be different on other planets
This is because of the gravitational force difference on each planet
If you weigh 75 pounds on Earth, which is 332 N, on Mars you would be 126 N and 782 on Jupiter

29. e. temperature
Physical property of temperature is related to how hot or cold an object is
A measure of kinetic energy, or energy of motion, of the particles that make up matter
Fahrenheit and Celsius are the most common forms of temperature scales
Thermometer is a tool used to measure temps
Kelvin (K) is the SI unit for temperature

30. f. Time and rates Time is an interval between two events
SI unit of time is second (s)
Hour (h) is not an SI unit but it is used for long periods of time
Rate – the amount of change of one measurement in a given amount of time
Speed is the most familiar rate in which the SI unit is kilometers per hour (km/h)
You don’t have to use km/h to measure speed but you can use measurement of an object during an event such as how many cars pass through an intersection per hour (cars/hour)

31. Drawings, tables, and graphs
2.3

32. a. Scientific illustrations
A.1. Drawings
Sometimes best choice to show details
Drawing can emphasize only the things that are necessary to show
If something tends to be the same color, the drawing can depict the different layers

33. A drawing can also show something difficult to see such as the solar system or the whole Earth

34. Quick sketches help to model problems
Such as drawing the outline of two continents and finding if they fit together

35. Drawing can show hidden things such as the water cycle or what the inside of a building looks like or where muscles in your arm are

36. a.2. PHotographs
Still photographs shows an object exactly as it is at a single moment in time
Movies show how an object moves and can be slowed down or sped up to show interesting features

37. b. Tables and graphs