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A broad-brush introduction to the field. |
Introduction to Physics
Open most introductory physics textbooks and you will read that physics Physics is the study of space-time, matter, energy, motion, and light, and their interactions. Indeed, physics offers understanding of the natural world that is awe-inspiring in its scope and precision: explaining the properties of atoms, how the moon, stars, and galaxies move, and how gravitation generated their obvious lumpiness starting with a big bang uniform except for tiny quantum fluctuations of extra density Its goal is accurate quantitative understanding, and its scope is the natural world. It studies the origin of the universe and the structure and behavior of all its constituents, including the quantum world of atoms and the macroscopic world of gas, liquid, solid, plasma and other objects constructed from these. Its scope is breathtaking, for example explaining the tiny quantum fluctuations (mandated by the uncertainty principle) and how these led through the action of gravitation to the large scale structure of the universe. Physics allows you to notice significant things about the natural world and to explain them, like why . For example, it explains not only the way H2O molecules exist in gas, liquid, and solid forms, and but also why these forms of matter are so fundamental that water co-exists in all three forms at water's triple point rather than simple turning into a simultaneously at the Triple Point, rather than as a homogeneous soft paste.
This understanding and insight is possible because physics is a science - a continuing process in which hypotheses that survived survive every well-done experimental test of their predictions against the actual behavior of the natural world are deemed to be "Laws of Nature". (sometimes Sometimes these Laws are called "theories," even though this word does not generally carry the requirement of an experimental test). In fact, physics underlies all the other physical sciences: chemistry, biology, and even more specialized sciences like materials science, environmental science, earth planetary science, and geology, etc. And following from these understandings, it enables whole These sciences, in turn, underlie entire fields of practical application called engineering : mechanical, electrical, civil, aeronautical, etcand biological among others.
Physics as a way of thought
Historically, physics formed the core of the discipline called "Natural Philosophy". "Philosophy" , which correctly emphasizes that physics is much more than a collection of facts, physical laws, and formulae - it is a powerful way of thinking about, and making sense of, the physical universe that we inhabit. In order to understand the world-view provided by physics, and especially to apply its understanding and methodology to other areas, you must not only know the facts and some formulas, but you must also think like a physicist. This involves principally problem solving: organizing this your knowledge so that it can be applied (transferred) to new situations, and being able to reach reliable conclusions about these situations that are reliable and whose limitations and errors can be estimated quantitatively.
Cognitive Structure of Physics
To learn something well, you need to monitor your learning. Part of this is understand the intellectual components of your subject and how they assemble into larger units and into the whole. For example in Tennis you might learn various strokes (backhand, forehand, drop shot), assemble them into tactics (use the drop shot when the opponent is too far back), and ultimately combine all into a strategy (play long hard strokes that are safely in bounds to lengthen the game, tire your older opponent, and deny him opportunities to utilize his superior drop shots). In an intellectual discipline like physics, there are also components in your mind that build into larger units. Here is a way to think of the various levels:
Facts - definitions, properties like such as the density of iron or air, or the value of g, unit of distancethe Gravitational Constant g
Concepts -- fundamental ideas about nature e.g. Newton's Third Law
Procedures - e.g. how to define a system, or to draw a force diagram, or find the moment of inertia
Concepts -- e.g. Newton's Third Law
Concept clusters-e.g. Physical interactions result in forces on objects,
Representations - How to think about models, e.g. equations, graphs, pictures, wordsof an object about a given axis
Models - theoretical idealizations of the world , (e.g. Circular Motion, Energy, Momentum)
Hypotheses - are consistently and Laws of Nature - hypotheses (logically developed guesses theories about how nature worksLaws of Nature - hypotheses with no experimental exceptions in domain ) that have survived extensive experimental tests within their domains of validity
Experiments - careful observation of constructed situations that have ability to falsify Laws
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Strategic Knowledge - Your ability to recognize which of your physics knowledge (particularly the laws and models) apply to a newly encountered problem in physics.
It will be important in constructing your own internal map of introductory physics to keep these distinctions in mind. As your encounter new information, think about where it fits in this hierarchy. Then, to optimize your learning, figure out how to do dedicated practice in the particular areas where you are weakest