1. Scientific Measurements
Metric System
Scientific Measurements

2. Metric System Developed by the French in the late 1700’s.
Based on powers of ten, so it is very easy to use.
Used by almost every country in the world, with the notable exception of the USA.
Especially used by scientists.
Abbreviated SI, which is French for Systeme International.

3. Metric Prefixes
Regardless of the unit, the entire metric system uses the same prefixes.
Common prefixes are:
kilo = 1000
centi = 1/100th
milli = 1/1000th
1 meter = 100 centimeters= 1000 millimeters

4. Length Length is the distance between two points.
The SI base unit for length is the meter.
We use rulers or meter sticks to find the length of objects.

5. Mass Mass is the amount of matter that makes up an object.
A golf ball and a ping pong ball are the same size, but the golf ball has a lot more matter in it. So the golf ball will have more mass.
The SI unit for mass is the gram.
A paper clip has a mass of about one gram.
The mass of an object will not change unless we add or subtract matter from it.

6. Measuring Mass We use a triple beam balance to measure mass.
Gravity pulls equally on both sides of a balance scale, so you will get the same mass no matter what planet you are on.

7. Weight Weight is a measure of the force of gravity on an object.
Your weight can change depending on the force of gravity. The gravity will change depending on the planet you are on.
The SI unit for weight is the Newton (N).
Do you remember that Newtons are the unit for forces?

8. Gravity
Gravity is the force of attraction between any two objects with mass.
The force depends on two things:
more distance = less gravity = less weight
less distance = more gravity = more weight
more mass = more gravity = more weight
less mass = less gravity = less weight

9. Weight and Mass Jill Earth 1 gravity Moon 1/6th gravity Jupiter
2.5 gravities
On orbit
0 gravity
mass
30kg
weight
300N
50N
750N
0 Newtons
Notice that Jill’s mass never changes. Her mother will not allow us to take parts off her, or add parts to her, so her mass stays the same. Jill is 30kg of little girl no matter where she goes!

10. Volume Volume is the amount of space contained in an object.
We can find the volume of box shapes by the formula Volume = length x width x height
In this case the units would be cubic centimeters (cm3).
So a box 2 cm x 3 cm x 5cm would have a volume of 30 cm3
V = L x W x H

11. Base Units The base unit for volume is the Liter.
We measure volume with a graduated cylinder and record it in mL.

12. Graduated Cylinders
Liquids form curved, upper surfaces when poured into graduated cylinders
To correctly read the volume, read the bottom of the curve called the meniscus

13. Liquid Volume
When the metric system was created, it was decided that 1 cm3 of water would equal 1 milliliter of water and the 1 mL of water will have a mass of one gram.
1cm3 water =1 ml of water = 1 gram

14. Water Displacement
We can use water displacement to find the volume of objects that are not boxed shaped.
We can put water in a graduated cylinder. If a rock causes the level to rise from 7 to 9 ml, the the rock must have a volume of 2-mL.

15. Water Mass and Volume 1 cm3 water = 1 mL of water = 1 gram
So what would be the mass of 50 mL of water be?
50 grams
So what would be the mass of 1 liter of water be?
1 L = 1000 mL so its mass would be 1000 grams or a kilogram.

16. Density
Density is the amount of matter (mass) compared to the amount of space (volume) the object occupies.
We will measure mass in grams and
volume in ml or cm3

17. Density Formula Density is mass divided by volume.
Density = mass/volume
Remember, all fractions are division problems.
Since the unit for mass is grams, and the unit for volume is ml or cm3, then the unit for density is g/ml, or g/ cm3

18. Density Formula Wheel Mass
Formula wheels make it easy to solve density problems.
Cover the property you are trying to find, and do what is left over.
To find density, cover the word density. You have mass over volume remaining. So divide mass by volume to find density!
Mass
density
volume

19. Density Formula Wheel Mass
To find mass, you cover the word mass. You now have density times volume remaining.
To find volume, cover volume. You have mass over density remaining, so divide mass by density to find volume.
Mass
density
volume

20. Understanding Density
In the following illustrations, each will represent 1 cm3.
Each g will represent 1 gram.
Mass = 24g
Volume = 8 cm3
Density = 3g/cm3
g g g

21. In other words, there are 3 grams in every cm3.
g g g
In other words, there are 3 grams in every cm3.

22. Density Problem 2
g g
Mass = grams
Volume = 6 cm3
Density = 2 g/cm3
In English we say the density of the object is 2 grams in every cubic centimeter.

23. Water and Density
Since 1-gram of water has a volume of 1-mL, then the density of water will always be 1 gram/ml.
5o-mL of water will have a mass of 50 grams, so again the density of pure water will be 1 g/ml.
A kg of water will have a volume of 1000-mL, so it’s density will be 1 gram/ml.

24. Floating and Sinking
Less dense materials will float on top of more dense materials.
Objects with a density of less than 1-g/mL will float on top of water.
Objects with a density greater than 1 g/mL will sink in water.

25. Neutral Buoyancy
Objects with a density equal to the density of water will float in mid water, at what ever level you place the object.
Fish and submarines control their depth by changing their density.

26. Objects that Sink!
Objects with a density greater than 1 g/mL will sink in water.

27. Titanic Sails the Ocean Blue
The Titanic is sailing on its maiden voyage.
What is the density of this enormous, steel hulled ship, full of machinery, coal, people, and all sorts of heavy things?
It’s floating, so it’s density must be less than 1 g/mL.
How can this be?
The Titanic is a hollow vessel full of air!

28. Titanic verses Iceberg
After HMS Titanic struck the iceberg, she started to fill with water.
What happened to her density?
As she took on more and more water, her density got closer and closer to 1 g/mL.
The denser the ship became, the lower she settled into the water.

29. Wreck of the Titanic
What is the density of the Titanic resting on the ocean floor?
Must be greater than 1 g/mL, as her steel hull is full of water instead of air.

30. Comparing Densities Where is the most dense object?
Where is the least dense object?

31. Density Review
We don’t actually count g’s to find the mass of objects. How would you find the mass of a rock?
Use a triple beam balance (or digital scale).
A rock is an irregular solid. How would you find the volume of a rock?
Use a graduated cylinder and see how much water the rock displaces.

32. International System of Units (SI)
Metric System
International System of Units (SI)

33. Basic Metric Units Length Mass Volume Temperature Time Meter (m)
Gram (g)
Liter (l)
Celsius (°C) or Kelvin (K)
Second (s)
Length
Mass
Volume
Temperature
Time

34. Derived Units
Area – amount of surface included within a set of boundaries; expressed in square units of length, e.g., m2
Volume – amount of space occupied by an object, e.g., m3 for solids or mL or L for liquids
Density – amount of matter that occupies a given space; mass/volume, e.g., g/mL

35. Basic units: m, L, g Many M mega 1 000 000 (106)
Kids k kilo (103)
Have h hecto (102)
Dropped da/dk deka (101)
Over Basic/BASE UNIT (ONES) (100)
Dead d deci (10-1)
Converting c centi (10-2)
Metrics m milli (10-3)
m micro (10-6)
n nano (10-9)
A Angstrom (10-10)

36. Many kids have dropped over dead converting metrics
Bigger to smaller - Move decimal right
Smaller to bigger - Move decimal left 3 3 3
100 (m, l, g)
Basic Unit M k h da d c m μ n
Many kids have dropped over dead converting metrics
4.22
422. cm = m
6523. m m = m
69631 ml
69.63 l =
13 dal =
130,000 ml kg
230 mg =
0.230 g
9.23 g =

37. Scientific Notation Form: N X 10x
N = number greater than 1, but less than 10
x = exponent of 10 (number of decimal places
Locate decimal and move it so that there is only one non-zero digit to its left (N)
Count the number of places you had to move the decimal
To the left, then x equals a positive number
To the right, then x equals a negative number

38. Scientific Notation N X 10x
Moving Decimal to Left = x
Moving Decimal to Right = --x N=
6.238
x = 3
6.238 X 103 N=
2.1536
x = 2
X 102 N=
6.32
x = -4
6.32 X 10-4 N=
1.852
x =
1.852 X 100 N=
1.35
x = 3
1.35 X 103
x = -1 N=
1.202
1.202 X 10-1

39. Celsius The Metric Temperature Scale
Also called the centigrade scale.
Definitions
0°Celsius(C) = 32°Fahrenheit(F) = water freezes
100°Celsius = 212°Fahrenheit = water boils
Conversions
°Celsius = 5/9 X (°Fahrenheit - 32°)
°Fahrenheit = (9/5 X °Celsius) + 32°
30 is hot,
20 is nice,
10 is chilly,
0 is ice.