1. Chapter 1: Measurement

2. Many properties of matter are quantitative
The Metric System
Many properties of matter are quantitative
This means that matter can be measured
Measured quantities of matter must always be specified in units
The units used for scientific measurement are those of the metric system

3. Units of the Metric System These units are called SI units
The metric system is a base-ten decimal system: Each unit is ten times larger than the next smaller unit
In 1960, an international system of metric units was agreed upon for use in scientific measurement
These units are called SI units

4. Prefixes used in the metric system
Symbol
Unit
Scientific
mega- M
1,000,000.0
10^6
kilo- k
1,000.0
10^3
hecto- h
100.0
10^2
deka- da
10.0
10^1
meter (base) m
1.0
10^0
deci- d
0.1
10^-1
centi- c
0.01
10^-2
milli-
0.001
10^-3
micro- μ
10^-6
Nano N
10^-9

5. Metric Conversions using Dimensional Analysis
The key to using dimensional analysis is the correct use of conversion factors
What is a conversion factor?
A conversion factor is a fraction whose numerator and denominator are the same quantity expressed in different units

6. Example of a conversion factor:
Inches to centimeters
Both the numerator and the denominator are expressing the same quantity of length using different units

7. Unit When using conversion factors, we want the given units to cancel
Then we end up with the desired units
Unit
Example: Using conversion factors, convert 6.25 inches to centimeters

8. ? Step 1: Use our inches-to-centimeters conversion factor
Question: Which one do we use? or ?

9. Step 2: Set up the calculation like this
Answer: We want the desired unit in the numerator of the conversion factor
Step 2: Set up the calculation like this
The inch units cancel, and we are left with centimeters, our desired unit

10. Let’s use conversion factors to express 2.6 meters as millimeters:
Here are the conversion factors we need:

11. Always set up your calculations so that given units cancel, and you get the desired units at the end

12. Scientific Method

13. Science and Induction
Scientific investigation can lead to important conclusions based on a type of logic called inductive reasoning
An inductive conclusion is a generalization that summarizes many concurrent observations
Observation
General Principle

14. Example: All the swans at Lake Mead are white in color
All the swans at Lake Powell are white in color
All the swans at Lake Michigan are white in color
All the swans at Lake Okeechobee are white in color
Argument: Therefore, all swans are white

15. There is a big problem with this argument:
This is inductive reasoning: The argument that all swans are white is a generalization made from many specific observations
Observation
General Principle
There is a big problem with this argument:
What is it?

16. If someone finds a black swan at another lake somewhere, our argument, or theory, is no longer valid

17. Deductive logic differs from inductive logic
When using deductive logic, we go from general premises to specific conclusions
Who is this guy?

18. This is Socrates, and we’ll use him in an example of deductive logic

19. Therefore, Socrates is mortal
All men are mortal
Socrates is a man
Therefore, Socrates is mortal
Or…
All organisms are composed of tiny cells
Socrates is an organism
Therefore, Socrates is composed of tiny cells

20. General Premises
Specific Conclusion
In the process of science, the deduction usually takes the form of predictions about what the outcomes of our experiments or observations should be
We then test the hypothesis by performing an experiment to see whether or not the results are as predicted

21. As a formal process of inquiry, the scientific method consists of a series of steps.
Most science is far less structured than presented here.
The key element here is the use of hypothetico-deductive reasoning.

22. Hypothetico-Deductive Reasoning
My flashlight doesn’t work
Hypothetico-Deductive Reasoning
What’s wrong with my flashlight?
The batteries are dead
If I my hypothesis is correct…
…and I replace the batteries

23. My flashlight should work!
Then:
My flashlight should work!
But what if my flashlight still doesn’t work?

24. Alternative hypotheses: The bulb is burned out…
We can always generate alternative hypotheses and test them in the same manner…
Alternative hypotheses:
The bulb is burned out…
The contacts are corroded…
The on-off switch is broken…

25. One black swan can disprove our theory that all swans are white
The point here is that any one of these hypotheses can be tested according to the scientific method
It is also important to note that all these hypotheses are falsifiable under the scientific method
Remember our theory about the swans: according to the scientific method we look for evidence that disproves our theory
One black swan can disprove our theory that all swans are white

26. Experimental
Design

27. In order to test a hypothesis we must design a suitable experiment
Experiments
In order to test a hypothesis we must design a suitable experiment
When performing our experiment, we must look for results relating to our hypothesis
These results will either support or not support our hypothesis

28. I will use plants grown hydroponically (in water rather than soil)
I want to conduct an experiment to identify essential nutrients required in plants
I will use plants grown hydroponically (in water rather than soil)
One group of plants will grow in an aqueous solution of complete nutrients
Another group of plants will grow in a solution lacking one nutrient

29. Hydroponic Farming

30. The control group allows us to compare with the experimental group
Our plants growing in a complete nutrient solution is called the control group
Our plants growing in a solution missing one nutrient is called the experimental group
The control group allows us to compare with the experimental group
If the missing nutrient has an effect on the experimental plants, their appearance should be different than the control group plants

32. What about the variables?
For our experiment to succeed, we must identify all of the variables
One variable is the growth response of the plants in the incomplete nutrient solution
Another variable is the difference in the experimental nutrient solution

33. We call this variable the independent variable
The incomplete nutrient solution is the variable that we, as investigators, are manipulating
We call this variable the independent variable
We will measure the effect of the independent variable on the growth of the plants
The response of the plants to the altered nutrient solution is called the dependent variable

34. We call the response of the plants the dependent variable because the magnitude of the response “depends” on how we manipulate the independent variable

35. Homework
1. Create your own experiment using the scientific method.
2. Set it up like the flashlight experiment showing all steps of the scientific method
3. It can be simple like the flashlight or more complicated like the growth of the plant
4. You should list all the steps of the scientific method and show how your experiment follows these steps