1. CHAPTER 2 Science, Matter, Energy, and Systems

2. Core Case Study: A Story About a Forest
Hubbard Brook Experimental Forest in New Hampshire
Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)
Stripped site:
30-40% more runoff
More dissolved nutrients
More soil erosion

3. The Effects of Deforestation on the Loss of Water and Soil Nutrients
Figure 2.1: This controlled field experiment measured the effects of deforestation on the loss of water and soil nutrients from a forest. V–notched dams were built at the bottoms of two forested valleys so that all water and nutrients flowing from each valley could be collected and measured for volume and mineral content. These measurements were recorded for the forested valley (left), which acted as the control site, and for the other valley, which acted as the experimental site (right). Then all the trees in the experimental valley were cut and, for 3 years, the flows of water and soil nutrients from both valleys were measured and compared.
Fig. 2-1, p. 31

4. 2-1 What Do Scientists Do?
Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.

5. Science Is a Search for Order in Nature (1)
Identify a problem
Find out what is known about the problem
Ask a question to be investigated
Gather data through experiments
Propose a scientific hypothesis

6. Science Is a Search for Order in Nature (2)
Make testable predictions
Keep testing and making observations
Accept or reject the hypothesis
Scientific theory: well-tested and widely accepted hypothesis

7. The Scientific Process
Figure 2.2: This diagram illustrates what scientists do. Scientists use this overall process for testing ideas about how the natural world works. However, they do not necessarily follow the order of steps shown here. For example, sometimes a scientist might start by coming up with a hypothesis to answer the initial question and then run experiments to test the hypothesis.
Fig. 2-2, p. 33

8. Nothing happens when I try to turn on my flashlight.
Observation:
Nothing happens when I try to turn on my flashlight.
Question: Why didn’t the light come on?
Hypothesis: Maybe the batteries are dead.
Test hypothesis with an experiment: Put in new batteries and try to turn on the flashlight.
Result: Flashlight still does not work.
New hypothesis: Maybe the bulb is burned out.
Figure 2.3: We can use the scientific process to understand and deal with an everyday problem.
Experiment: Put in a new bulb.
Result: Flashlight works.
Conclusion: New hypothesis is verified.
Fig. 2-3, p. 33

9. Characteristics of Science…and Scientists
Curiosity
Skepticism
Reproducibility
Peer review
Openness to new ideas
Critical thinking
Creativity

10. Science Focus: Easter Island: Revisions to a Popular Environmental Story
Some revisions to a popular environmental story
Polynesians arrived about 800 years ago
Population may have reached 3000
Used trees in an unsustainable manner, but rats may have multiplied and eaten the seeds of the trees

11. Stone Statues on Easter Island
Figure 2.A: These and many other massive stone figures once lined the coasts of Easter Island and are the remains of the technology created on the island by an ancient civilization of Polynesians. Some of these statues are taller than an average five-story building and can weigh as much as 89 metric tons (98 tons).
Fig. 2-A, p. 35

12. Scientific Theories and Laws Are the Most Important Results of Science
Scientific theory
Widely tested
Supported by extensive evidence
Accepted by most scientists in a particular area
Scientific law, law of nature

13. Science Has Some Limitations
Particular hypotheses, theories, or laws have a high probability of being true while not being absolute
Bias can be minimized by scientists
Environmental phenomena involve interacting variables and complex interactions
Statistical methods may be used to estimate very large or very small numbers
Scientific process is limited to the natural world

14. 2-2 What Is Matter?
Concept 2-2 Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.

15. Matter Consists of Elements and Compounds
Has mass and takes up space
Elements
Unique properties
Cannot be broken down chemically into other substances
Compounds
Two or more different elements bonded together in fixed proportions

16. 2-3 What Happens When Matter Undergoes Change?
Concept 2-3 Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

17. Matter Undergoes Physical, Chemical, and Nuclear Changes
Physical change
No change in chemical composition
Chemical change, chemical reaction
Change in chemical composition
Reactants and products
Nuclear change
Natural radioactive decay
Radioisotopes: unstable
Nuclear fission
Nuclear fusion

18. Types of Nuclear Changes
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Fig. 2-9, p. 43

19. We Cannot Create or Destroy Matter
Law of conservation of matter
Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed

20. 2-4 What is Energy and What Happens When It Undergoes Change?
Concept 2-4A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).
Concept 2-4B Whenever energy is changed from one form to another in a physical or chemical change, we end up with lower-quality or less usable energy than we started with (second law of thermodynamics).

21. Energy Comes in Many Forms (2)
Sun provides 99% of earth’s energy
Warms earth to comfortable temperature
Plant photosynthesis
Winds
Hydropower
Biomass
Fossil fuels: oil, coal, natural gas

22. Energy Changes Are Governed by Two Scientific Laws
First Law of Thermodynamics
Law of conservation of energy
Energy is neither created nor destroyed in physical and chemical changes
Second Law of Thermodynamics
Energy always goes from a more useful to a less useful form when it changes from one form to another
Light bulbs and combustion engines are very inefficient: produce wasted heat

23. Energy-Wasting Technologies
Figure 2.16: Two widely used technologies waste enormous amounts of energy. In an incandescent lightbulb (right), about 95% of the electrical energy flowing into it becomes heat; just 5% becomes light. By comparison, in a compact fluorescent bulb (left) with the same brightness, about 20% of the energy input becomes light. In the internal combustion engine (right photo) found in most motor vehicles, about 87% of the chemical energy provided in its gasoline fuel flows into the environment as low-quality heat. (Data from U.S. Department of Energy and Amory Lovins; see his Guest Essay at CengageNOW.)
Fig. 2-16a, p. 48

24. 2-5 What Are Systems and How Do They Respond to Change?
Concept 2-5 Systems have inputs, flows, and outputs of matter and energy, and feedback can affect their behavior.

25. Systems Have Inputs, Flows, and Outputs
Set of components that interact in a regular way
Human body, earth, the economy
Inputs from the environment
Flows, throughputs of matter and energy
Outputs to the environment

26. Inputs, Throughput, and Outputs of an Economic System
Figure 2.17: This diagram illustrates a greatly simplified model of a system. Most systems depend on inputs of matter and energy resources, and outputs of wastes, pollutants, and heat to the environment. A system can become unsustainable if the throughputs of matter and energy resources exceed the abilities of the system’s environment to provide the required resource inputs and to absorb or dilute the resulting wastes, pollutants, and heat.
Fig. 2-17, p. 48

27. Systems Respond to Change through Feedback Loops
Positive feedback loop
Causes system to change further in the same direction
Can cause major environmental problems
Negative, or corrective, feedback loop
Causes system to change in opposite direction

28. Positive Feedback Loop
Figure 2.18: This diagram represents a positive feedback loop. Decreasing vegetation in a valley causes increasing erosion and nutrient losses that in turn cause more vegetation to die, resulting in more erosion and nutrient losses. Question: Can you think of another positive feedback loop in nature?
Fig. 2-18, p. 49

29. Negative Feedback Loop
Figure 2.19: This diagram illustrates a negative feedback loop. When a house being heated by a furnace gets to a certain temperature, its thermostat is set to turn off the furnace, and the house begins to cool instead of continuing to get warmer. When the house temperature drops below the set point, this information is fed back to turn the furnace on until the desired temperature is reached again.
Fig. 2-19, p. 50

30. Time Delays Can Allow a System to Reach a Tipping Point
Time delays vary
Between the input of a feedback stimulus and the response to it
Tipping point, threshold level
Causes a shift in the behavior of a system
Melting of polar ice
Population growth

31. System Effects Can Be Amplified through Synergy
Synergistic interaction, synergy
Two or more processes combine in such a way that combined effect is greater than the two separate effects
Helpful
Studying with a partner
Harmful
E.g., Smoking and inhaling asbestos particles

32. The Usefulness of Models for Studying Systems
Identify major components of systems and interactions within system, and then write equations
Use computer to describe behavior, based on the equations
Compare projected behavior with known behavior
Can use a good model to answer “if-then“ questions

33. Three Big Ideas There is no away.
You cannot get something for nothing.
You cannot break even.