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Exam 1 3 Dynamic Equilibrium 1.A system changes around a changing average. Threshold 1.Big change in a system after a small change in inputs or outputs. “straw on camel’s back”Negative & Positive Feedback 1.Negative—keeps system in equilibrium, self-regulating system—returns to equilibrium after perturbation 2.Positive—keeps changing, goes out of equilibrium Lags 1.Delay in system changes System Resilience 1.Way in which a system reacts to a change. 2.Relaxation time—time it takes for system to return to equilibrium Cycles & Budget 1.Earth is closed system. Materials are finite, while energy enters and leaves system 2.Budget—amount of a material in each form it can have Origins: Astronomical Background Solid, Liquid, Gas, Plasma 1.Solid—fixed in position, and have low kinetic energy 2.Liquid—free to move, definite volume, and have more kinetic energy than solids 3.Gas—great deal of space between particles, will spread indefinitely if able to 4.Plasma—matter is hot enough for the electrons to be separated from the nuclei Atoms & Molecules 1.Atoms—building blocks of matter, and made up of protons, neutrons, and electrons. Nucleus holds protons and electrons. Electrons orbit nucleus 2.Molecules—atoms stuck together Protons, Neutrons, Nucleus 1.Protons—positive charge, determines element 2.Neutrons—no charge 3.Nucleus—made up of protons and neutrons Electrons 1.Negative charge 2.Same number of protons as electrons. 3.Orbit nucleus
Geography 1401 Dr. Jeff Lee Exam 1 4 Electromagnetic Force 1.Things are either positive, negative, or neutral 2.Positive is attracted to negative and vice-versa 3.Like charges repel each other 4.Attraction and repulsion decreases with distance 5.(Magnetism is a form of electrical force) 6.EM holds atoms and molecules together Strong and Weak Forces 1.Strong—work within nucleus 2.Positive things are held together in nucleus because force is greater than EM in nucleus Gravitational Force 1.Any two things are attracted to each other 2.Strength depends on mass and distance 3.Strongest force beyond atomic scale Big Bang 1.14B years ago (best estimate) all of the universe in a tiny ball of energy, very hot 2.Energy can turn into mass 3.BOOM 4.As energy expanded, it cooled 5.First second: subatomic particles formed, strong and weak forces created protons and neutrons, forming nuclei of hydrogen and deuterium (& some helium) 6.Nothing happened for a few hundred million years 7.When temperature dropped to a few thousand degrees, EM came into play Formation of Galaxies & Solar System 1.Galaxy a.Some areas had more mass than others and gravity pulled these into masses called galaxy clusters b.Within clusters, denser areas were pulled together to form galaxies c.Within galaxies, stars started to form 2.Solar system a.Around 4.6B years ago, interstellar dust began to coalesce in a big rotating disk b.Most mass converged at the center, forming the sun c.Rest circled the sun Creation of Hydrogen & Helium 1.