patrik

Basic Concepts in Physics

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Hi! I'm about to go nuts trying to understand the basic concepts which highschool physics is founded upon.

What are these things, exactly?

  • Mass
  • Force
  • Energy
  • Charge
  • Field

I'm not looking for the cause or explanation for these phenomena, I just want to understand what books and teachers are saying.

Mass as I understand it is a measure of an objects inertia, or resistance to being accelerated. Feel free to correct as you like.

The one I have biggest problem with atm. (and perhaps the reason for my confusion on the rest of them) is the concept Force (F).

It is said that force is the cause of movement. a "push" or "pull". But if i push a glass on the table next to me (applying OPAR reasoning here) isn't the cause of the glass moving my hand, and not some mysterious force? Second example: If I throw a ball it will fall to the ground. My teacher says the ball falls because of the force of gravity. But isn't force just a way of explaining motion? If that is true then saying that it falls because of the force of gravity is like saying that it falls because it falls. Can a force really be the cause of movement..isn't it just a way of describing movement (or acceleration)? I don't understand how to apply this concept.

Could someone help me understand these concepts, and relate them to Objectivist epistemology? That would be great. I bet there are lots of confused students in need of this discussion.

I've carefully read OPAR and ITOE so I have some basic understanding of Objectivism.

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The one I have biggest problem with atm. (and perhaps the reason for my confusion on the rest of them) is the concept Force (F).

It is said that force is the cause of movement. a "push" or "pull". But if i push a glass on the table next to me (applying OPAR reasoning here) isn't the cause of the glass moving my hand, and not some mysterious force?

How did your hand move it? By pushing on the glass with a force. Your hand didn't move it by snapping its fingers and saying abracadabra.
Second example: If I throw a ball it will fall to the ground. My teacher says the ball falls because of the force of gravity. But isn't force just a way of explaining motion? If that is true then saying that it falls because of the force of gravity is like saying that it falls because it falls.
The force of gravity is perceivable independent of falling motion. When you sit in a chair, don't you feel the force of gravity on your body squishing you down? Why do the oceans stay bound to the Earth's surface even though the Earth is rotating?
Can a force really be the cause of movement..isn't it just a way of describing movement (or acceleration)? I don't understand how to apply this concept.
An object cannot spontaneously change its state of motion. Any change in state of motion must be accompanied by some net-force that caused it. The force itself will have some physical origin.

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Hi! I'm about to go nuts trying to understand the basic concepts which highschool physics is founded upon.

What are these things, exactly?

  • Mass
  • Force
  • Energy
  • Charge
  • Field

I'm not looking for the cause or explanation for these phenomena, I just want to understand what books and teachers are saying.

Mass as I understand it is a measure of an objects inertia, or resistance to being accelerated. Feel free to correct as you like.

The one I have biggest problem with atm. (and perhaps the reason for my confusion on the rest of them) is the concept Force (F).

It is said that force is the cause of movement. a "push" or "pull". But if i push a glass on the table next to me (applying OPAR reasoning here) isn't the cause of the glass moving my hand, and not some mysterious force? Second example: If I throw a ball it will fall to the ground. My teacher says the ball falls because of the force of gravity. But isn't force just a way of explaining motion? If that is true then saying that it falls because of the force of gravity is like saying that it falls because it falls. Can a force really be the cause of movement..isn't it just a way of describing movement (or acceleration)? I don't understand how to apply this concept.

Could someone help me understand these concepts, and relate them to Objectivist epistemology? That would be great. I bet there are lots of confused students in need of this discussion.

I've carefully read OPAR and ITOE so I have some basic understanding of Objectivism.

Force is not the cause of movement as objects at constant velocity have no net force acting on them (the force being in the direction of motion). Force causes a change in movement due to acceleration. When a plane if flying at constant velocity, drag = thrust, lift = gravitational acceleration. Of course, a force is produced by interactions among entities. The concept force is an abstract method of describing the motion of objects and how they interact with other objects.

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Force is not the cause of movement as objects at constant velocity have no net force acting on them (the force being in the direction of motion).

What caused them to move in the first place?

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I would say more but I guess I'm a little confused by your request.

Do you simply want some good resources to learn from, or do you need some concepts explained to you?

Are you teaching physics, are you a high school physics student?

For a free, online reference, I'd recommend Hyperphysics:

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

I would avoid sites like Wikipedia. Physics articles in Wikipedia are often useless for people learning, as they casually reference concepts that will be floating abstractions for the audience they seek to explain the material to. Also oftentimes wikipedia physics entries are just the stitched together copy-pasted passages from copyrighted textbooks.

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Force is not the cause of movement as objects at constant velocity have no net force acting on them (the force being in the direction of motion).

What caused them to move in the first place?

Paul meant that force does not cause movement in the sense of constant, straight line motion. A net force acting on an object changes its state of motion, which means its speed and/or direction.

The natural state of motion of an object free of forces is constant, straight line motion.

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Paul meant that force does not cause movement in the sense of constant, straight line motion. A net force acting on an object changes its state of motion, which means its speed and/or direction.

The natural state of motion of an object free of forces is constant, straight line motion.

I agree, but I don't like the wording. I asked that question specifically to get to the root of, and avoid the confusion caused by: "Force is not the cause of movement..." Any movement necessarily pre-supposes the action of a force does it not? To a student, I'd rather be consistent from the beginning.

I was taught the physics of motion using Newton's laws of classical mechanics, and I think it is the proper approach for someone to whom these concepts are new. The last thing I'd want to do is cause any confusion, however small, in the mind of a student. In electronics, I had such a hard time understanding some simple concepts because of unnecessary confusion caused by imprecise language. I held on to these misunderstandings for years until I got to the workplace and found out how things really are.

My physics is more than a little rusty now but I find the following to be an example of precise, unambiguous language:

"Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by a force impressed on it."

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Paul meant that force does not cause movement in the sense of constant, straight line motion. A net force acting on an object changes its state of motion, which means its speed and/or direction.

The natural state of motion of an object free of forces is constant, straight line motion.

I agree, but I don't like the wording. I asked that question specifically to get to the root of, and avoid the confusion caused by: "Force is not the cause of movement..." Any movement necessarily pre-supposes the action of a force does it not? To a student, I'd rather be consistent from the beginning.

--------------

I don't think there is any confusion by my statement. Force simply produces a change in movement, i.e., an accelerated movement, not necessarily the movement itself, if the movement is not accelerated. It is irrelevant what caused the initial movement to understanding what force is. And if you really want to be precise, there is nothing in the universe that is not moving relative to something else. "At rest" simply means movement at the same rate (velocity) as the reference frame of an observer.

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It's not clear to me that the question of what the concept "force" refers to has been answered adequately (in the context of the science of physics). Doesn't the concept of "force" typically arise initially when a child pushes or pulls on something, and it resists -- or when something pushes or pulls on the child, and the child resists? "Force" is simply that which pushes or pulls, the actual pushing or pulling action, not the thing that initiatiates the action.

In relation to causality, force is the interaction or mechanism by which one entity acts upon another. Force can be thought of as the action produced by an entity, often resulting in effects on other entities.

Mass is simply the bulk of an entity (not volume), which gives the entity weight when subjected to the pull of another large object such as the Earth, and inertia when acted upon by other entities exerting forces on it. A child probably first learns of "mass" as closely related to what the child can readily experience as weight, but abstracted away from any particular gravitational field. A child may also experience it as the pull of a heavy object when swung rapidly around on the end of a rope, or the resistance of a loose object when a child tries to throw it, or catch it when someone or something else sets it in motion. Mass specifically refers to the "heaviness" of the object, not necessarily the actual force of moving or stopping it.

"Field," in turn, is just a region in which there is a force of some kind, such as a gravitational force or an electrical force. Quantitatively, the total force is usually proportional to the mass (for gravity) or charge (for electrical force), so the intensity of the field is measured as force per unit of mass, or force per unit of charge.

Newton's Laws, in part, relate force, acceleration and mass very precisely (F=ma).

Acceleration wasn't mentioned in the original list, but it's just the rate of change of velocity, which, in turn, is the rate of change of position or distance. To go much farther with the concept of "rate of change" in a quantitative way, one will probably need some calculus, especially if the velocity is varying (not constant) -- although it's possible to teach an entire first semester college course in "Mechanics, Heat and Sound" without formally introducing calculus.

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Thank you for those responses.

I got the opportunity to study physics in one of the finest universities in my country, and I'm on my way to do so because I find it fascinating.

At the moment I am taking highschool-level prep-classes in physics and math before I start the real program. My aim here is to develop my philosophical understanding better from the start. I want to really understand what I'm doing. So my mind won't become "compartmentalized" later on. :) I mean I don't want to be a problem-solving machine, my goal is to be creative with these ideas.

To answer your question carlos I'm looking to get these concepts explained better than my teacher can, due to being a complete platonist. I had been reading a bunch of Objectivist litterature before starting this semester and boy, I just start laughing every time he adds some stupid thing like: "Imaginary numbers do not exist in reality, but in another world".

To start with, it would help if someone could answer these questions I have about forces:

1. How do you know whether or not you observe a force? What characteristics must be there?

(It seems to me that if the unit Newton is 1 kgm/(s^2), it requires something with mass accelerating for there to be a force. Please comment on this.)

2. In what way do forces exist, what are they?

3. How do you go from that understanding to proceed to measure forces mathematically? Whence the unit 'Newton'?

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Thank you for those responses.

I got the opportunity to study physics in one of the finest universities in my country, and I'm on my way to do so because I find it fascinating.

My undergraduate degree was in Physics, and I'm completing my Masters this summer. It's been a wild ride, but well worth it. Physics is infinitely beautiful and rewarding to study, but you need to get yourself ready to be challenged.

I say this without exaggeration: a degree in Physics is (from my experience) literally the most challenging degree you can obtain as an undergraduate student. No other field of study can compare in terms of level of abstraction, mathematical rigor, and overall complexity. If you are going to do this, you need to be ready to work really hard. The playtime of non-challenging highschool curriculum will be over, and for the first time in your life you will probably need to develop very serious study habits.

At the moment I am taking highschool-level prep-classes in physics and math before I start the real program. My aim here is to develop my philosophical understanding better from the start. I want to really understand what I'm doing. So my mind won't become "compartmentalized" later on. :) I mean I don't want to be a problem-solving machine, my goal is to be creative with these ideas.

To answer your question carlos I'm looking to get these concepts explained better than my teacher can, due to being a complete platonist. I had been reading a bunch of Objectivist litterature before starting this semester and boy, I just start laughing every time he adds some stupid thing like: "Imaginary numbers do not exist in reality, but in another world".

Something I want to warn you about that was very damaging for me, is how corrupted of a view of physics you can gain from many highschool physics classes.

Most highschool physics classes are taught purely with algebra, with most equations and principles being given as axioms or on faith, with no derivations or proofs. Most highschool physics problems are solved by memorizing a laundry list of different equations, and then simply applying them or algebraically manipulating them for each problem. This is not what real physics is like. Real physics is about creatively deriving the equations you need, according to the the fundamental principles of physics that are pertinent to what you are studying. In Classical Electrodynamics for example, you'll probably always start from the Maxwell Equations, and for each problem find a way to creatively attack it in the most mathematically efficient way to get at what you want. This is one of the most valuable skills you'll gain from physics: being able to approach and solve very nonlinear mathematical problems (by nonlinear I mean not straightforward, as in there are multiple ways to solve it).

To start with, it would help if someone could answer these questions I have about forces:

1. How do you know whether or not you observe a force? What characteristics must be there?

(It seems to me that if the unit Newton is 1 kgm/(s^2), it requires something with mass accelerating for there to be a force. Please comment on this.)

2. In what way do forces exist, what are they?

3. How do you go from that understanding to proceed to measure forces mathematically? Whence the unit 'Newton'?

In general force is equal to the change in linear momentum over time. Linear momentum has units of kg*m/s (mass times velocity). Something that is changing with respect to time will have units of s^-1, as you are referring to a quantity that changes by so many units per second.

A force of 1 Newton applied to an object will by definition change its linear momentum by 1kgm/s per second, which is 1kgm/(s^2).

For objects with mass, this can be viewed logically as 1Newton=(1kg)(1m/s^2), which is units of mass times acceleration.

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To start with, it would help if someone could answer these questions I have about forces:

1. How do you know whether or not you observe a force? What characteristics must be there?

Acceleration cannot happen without an applied force. If an object is changing its state of motion, there is a force at work. Objects cannot change their state of motion spontaneously. By "change its state of motion", I mean the object's speed and/or direction of motion changes.

If an object is accelerating, that means its velocity is changing. Velocity is a vector, with speed as its magnitude or scalar quantity. If the speed of an object is held constant but the direction of motion is changing, that is a change in velocity and must require a force. If the direction is held constant and the speed is changing, that is a change in velocity, and requires a force. If both change that is definitely a change in velocity, and definitely requires a force.

(It seems to me that if the unit Newton is 1 kgm/(s^2), it requires something with mass accelerating for there to be a force. Please comment on this.)

The absence of acceleration of an object doesn't mean there is an absence of forces on the object, it just means the sum of force applied to the object is zero. You feel gravity squishing you against the Earth now don't you? A skyscraper isn't accelerating, but there are obviously enormous forces at work on the main structural elements holding it up.

To be precise, in order for there to be acceleration, the total force must be non-zero. You are sitting in your chair feeling the force of gravity pulling you down, but you aren't accelerating, as the chair is pushing back up against you. The forces are equal and opposite, and sum vectorially to be exactly zero.

2. In what way do forces exist, what are they?

3. How do you go from that understanding to proceed to measure forces mathematically? Whence the unit 'Newton'?

By recognizing that objects cannot change their linear momentum spontaneously. For an object to change it's linear momentum requires a net-force acting on it, and the change in linear momentum over time is the net-force.

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As a suggestion Patrik, here's a practice I made a habit of in highschool physics that dramatically helped my understanding.

Whenever I encountered a new concept (such as "work") I would always do three things:

1: First, make sure I fully understand the sub-concepts from which the concept is constructed. If work is W=F*d, I would think about the units of force and distance, and what the units of work are and what that means physically.

2: Second, apply the concept to many different examples, so you can understand how to use it and how it works.

3: Last, relate it to other concepts you know in Physics. Understand the relation between work and kinetic energy, potential energy, etc.

After encountering Objectivism I realized these were the proper steps in integrating a concept:

1: Understand the concepts that subsume a higher concept

2: Be able to concretize the concept

3: Integrate it with the rest of your knowledge

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I got the opportunity to study physics in one of the finest universities in my country, and I'm on my way to do so because I find it fascinating.

At the moment I am taking highschool-level prep-classes in physics and math before I start the real program. My aim here is to develop my philosophical understanding better from the start. I want to really understand what I'm doing. So my mind won't become "compartmentalized" later on. :) I mean I don't want to be a problem-solving machine, my goal is to be creative with these ideas.

To start with, it would help if someone could answer these questions I have about forces:

1. How do you know whether or not you observe a force? What characteristics must be there?

You do not always directly observe forces. You do in situations where you can feel a push or a pull, but most of the time you infer the force from what else you do observe. The inference is in terms of what you know about physics theory in your ever-expanding knowledge of scientific concepts and principles. For example, you have to know a lot more to know that there are forces on electrons and the nature of those forces than you do to understand the force on an apple as it falls out of a tree.

(It seems to me that if the unit Newton is 1 kgm/(s^2), it requires something with mass accelerating for there to be a force. Please comment on this.)

No, there can be many forces of the different kinds acting on something without acceleration if the forces are balanced so that the net force is zero. The gravitational force on an apple is the same when it is falling as when it is stopped where it landed. You feel a force on a compressed spring whether or not your hand and the spring are moving or accelerating.

The numerical equivalence of units are derived relations; they do not cause the phenomena or create the laws. Always keep the hierarchy of concepts and principles straight in your mind. A standard unit of measurement of force is the newton, which is numerically equal to kg-m/s^2 in accordance with F=ma. That doesn't mean that there must be a mass accelerating before there can be a force. The causation is the other way around.

2. In what way do forces exist, what are they?

There is always a 'push or pull', to put it in elementary terms, but the manner in which that arises depends on what physical phenomenon and entities you are talking about. The list of 'ways that forces exist' that you can learn about grows with your knowledge of physics, from simple mechanics of single objects, to mechanics of elastic continua and fluids, to electricity and magnetism, to atomic physics, and more. The answer to the question "in what way do forces exist?" is a major topic and purpose of the subject of physics. It isn't something you answer in advance of pursuing the subject.

3. How do you go from that understanding to proceed to measure forces mathematically? Whence the unit 'Newton'?

You measure or infer the magnitude of forces using instruments and theoretical derivation in accordance with the principles of physics that apply to whatever the situation is.

You must choose a unit -- in this case some degree of force -- as in instance of the concept to use as a numerical standard of comparison in order to measure a physical characteristic. The choice of unit is optional, within restrictions that arise form the cognitive purpose of what you are doing. The newton is a unit that was chosen to avoid the unnecessary multiplicative factor in F=k*m*a. All the units in that equation are chosen to represent the order of magnitudes with which one ordinarily deals.

What are these things, exactly? Mass, Force, Energy, Charge, Field.

...

Mass as I understand it is a measure of an objects inertia, or resistance to being accelerated. Feel free to correct as you like.

Your list of concepts spans a broad range of levels of abstraction.

Mass (at an elementary level of understanding -- which is where you start), is quantity of matter in an object. A piece of lead has more mass than a piece of wood of the same volume. A bigger piece of lead has more mass than a smaller volume. A more massive object has both more weight and more inertial resistance to acceleration, and can be converted to more energy (E=mc^2). Gravitational force, weight and momentum are proportional to mass as the same attribute. These are facts about mass, and the mass referred to in each is the same concept (which is the meaning, for example, of the equivalence of the 'gravitational' and 'inertial' mass).

You measure mass, mass is not a "measurement" of inertia. Beware of the false philosophical approach that often appears in discussions of physics claiming that the concepts of physics are defined by how they are measured (called "operationism", a variety of Logical Positivism in philosophy).

The one I have biggest problem with atm. (and perhaps the reason for my confusion on the rest of them) is the concept Force (F).

It is said that force is the cause of movement. a "push" or "pull". But if i push a glass on the table next to me (applying OPAR reasoning here) isn't the cause of the glass moving my hand, and not some mysterious force? Second example: If I throw a ball it will fall to the ground. My teacher says the ball falls because of the force of gravity. But isn't force just a way of explaining motion? If that is true then saying that it falls because of the force of gravity is like saying that it falls because it falls. Can a force really be the cause of movement..isn't it just a way of describing movement (or acceleration)? I don't understand how to apply this concept.

Force does not "describe" acceleration, it causes it. You can only numerically equate the magnitude of a net force with mass * acceleration because you know Newton's law. That does not change the concept of force into descriptions of motion.

If your hand pushes on a table it may or may not move, but your hand is exerting the force on the table. The force does not exist by itself apart from your hand. When you speak of a force causing an acceleration, that is an abstraction -- for the purposes of understanding the result of the force it doesn't matter whether it is exerted by your hand or anything else, so that is omitted from the abstract statement. That omission doesn't mean that a hand or something else exerting the force does not exist.

Likewise with gravity "causing" a ball to fall: A gravitational force is due to the attraction between two objects. When you analyze motion of an object caused by gravity you are omitting consideration of one of the objects, the earth, because it doesn't matter in your analysis, which depends only on the force; it doesn't mean that the earth does not exist or has nothing to do with the force.

Likewise, the concept of gravitational 'field' omits the specific object subject to the pull near the earth; it is a higher level abstraction that pertains to all such objects of any mass. That does not mean that force exists without the presence of the object. It is the force that exists when any object is present, proportional to its mass. If you don't understand the concept and principles of higher levels of abstract concepts you won't understand what it means to say a gravitational field exists and you will wind up reifying the concept. (Electromagnetic fields are even more complex, to say nothing of Einstein's space-time.)

Could someone help me understand these concepts, and relate them to Objectivist epistemology? That would be great. I bet there are lots of confused students in need of this discussion.

I've carefully read OPAR and ITOE so I have some basic understanding of Objectivism.

In relating your understanding of physics to Introduction to Objectivist Epistemology, bear in mind that IOE does not deal specifically with how to apply the basic principles to scientific method, the philosophy of physics, the nature of theory-formation or its role in forming abstract technical concepts. (Such aspects beyond the scope of IOE are briefly referred in the appendix on the workshops.) Objectivism is general philosophy, which means it pertains to that which can be understood without specialized knowledge of the sciences.

Concepts of 'energy', 'fields', 'charge', and other concepts of physics are all much more abstract than even the technical concepts of 'mass' and 'force', and cannot be understood without more knowledge of physics and mathematics, and the facts that give rise to the concepts within the specialized study of physics. You cannot understand the epistemology of such abstract technical concepts in terms of general philosophy alone and observations available to anyone. A philosophy of science like physics is based on general epistemology, but depends in addition on the nature of the subject matter: the kinds of facts subsumed and the specialized knowledge and methods used to comprehend them.

So while a concept like 'charge' or 'field' requires high level abstractions from abstractions and advanced concepts of method whose epistemology belongs to the specialized philosophy of physics, this does not prevent you from following and understanding rational scientific explanations. Just don't expect to find a direct explanation of every philosophical question you have about physics in the discussion of general concept formation in IOE.

Identifying through abstract concepts the existence of 'charge', which cannot be directly observed, is much more complex than observing a macroscopic entity and directly abstracting the attribute 'length'. All you have to base it on is the macroscopic objects and measurements with wires, ammeters, torsion balances, etc. that you can observe and what you can infer through the elementary properties of electromagnetism that you learn, from which you ultimately infer the existence of subatomic-scale entities called electrons with charge.

Your abstract scientific understanding must be based on the facts that give rise to the concepts and principles, traced hierarchically to the basic facts you can observe directly, along with the purpose and function of the abstract mathematical formulations of concepts and their definitions. This allows you to form concepts and principles about things in reality that you cannot observe directly.

But there is more to his than the specifics of concept and theory formation. Be sure when you are searching for a philosophically proper understanding of any concept in physics that you know what a proper understanding consists of. You may read some explanation in physics and then ask, 'but what is it really'? The explanation may or may not be adequate, but make sure you are using the right standard.

One principle of Objectivism to keep firmly in mind to avoid philosophical confusion is the fundamental relation of existence and identity. That doesn't say that existence has identity, rather, existence is identity. A thing is all of its attributes, everything about it. Attributes are not something that are tacked onto a thing with some other kind of identity of its own and which you seek to uncover beneath the attributes. The attributes, all of them, are all there is.

This is helpful to remember when you try to understand abstract concepts like 'charge', 'energy' and 'fields', where you may be looking for some mysterous 'inner essence' that it 'really is'. There is no such mysterious underlying thing that you are missing. There is a lot you don't know, but these concepts are based on characteristics observed or inferred as attributes. The sum of the characteristics are what something is and are all it is; the ones you know about in your technical knowledge of physics are all you have on which to base your concepts and knowledge. You don't have to (and can't) know everything in order to know something. That your knowledge is limited does not prohibit you from holding valid abstract concepts. There is always more to know, more to question, and more to root out and discover so that knowledge can expand, but don't confuse scientific understanding with metaphysical quest for an unknown thing aside from its attributes, hiding from you behind the attributes that you do know.

You can understand the science in terms of legitimate scientific explanation, but in terms of contemporary educational methods, in order to understand the physics objectively and in the proper hierarchy you can't rely on common presentations in lectures and books in which the 'laws' are laid down without explanation of how and why they were discovered and what gave rise to the concepts, in which they only pay lip service to something called 'experiments'. A proper understanding comes only with some basic knowledge of the history of the science, the nature of the experiments, and the kind of reasoning employed in them to justify scientific principles.

This doesn't mean that you need to study the full history of physics now, because there is more in that than you need to know for the basic understanding you are seeking -- including all the false leads and the historical, more unnecessarily complex ways of thinking about and sorting through the initial confusion and early understanding. Learning more of the history will be important later to see what the development of a science is really like -- it doesn't just pop out of a sequence of experiments and ideas that just pop into someone's head. But that should come later after you understand the basics.

Some good sources on the empirical roots of basic physics are:

  • Klein, The Science of Measurement: A Historic Survey, Dover, 1974. This book covers all the basic branches of physics, focusing on the main concepts, what they mean, and how they are measured.
    Rothman, Discovering the Natural Laws: The Experimental Basis of Physics, Dover, 1972.
    Shamos, Great Experiments in Physics: Firsthand Accounts from Galileo to Einstein, Dover, 1987. Includes summaries of historical background and the context of the experiments.

You don't need to read those books in their entirety now, just the parts relevant to elementary physics that you are now learning about. They are mostly verbal and explanatory about the essentials, not highly mathematical or oriented towards solving mathematical problems.

You will eventually realize that studying physics on a 'high school' level can be more conceptually difficult than college physics because of the deliberate attempts to dumb it down and to avoid using more mathematics that is required to more simply and easily understand it. That approach only exacerbates the bad approach of memorizing rules.

You should also not restrict yourself to the one textbook assigned. By exploring different books as you proceed through the subject matter you will often find better explanations and useful information that you would otherwise miss.

Make sure you always understand the concepts and principles on which newly introduced concepts are based when they are introduced. If you don't do that your entire knowledge will disintegrate into floating abstractions and you will find that you are manipulating ideas as a so-called "model" in parallel with unknowable reality instead of knowledge of reality.

A couple of very useful older classics for basic college physics that you should have on hand for good conceptual explanations are:

  • Feynman, The Feynman Lectures on Physics, 3 volumes, Addison Wesley, 2nd edition (with corrections to the original 1963 original), 2005.
    Sears, Principles of Physics, Addison Wesley, 1950s editions. 1 - Mechanics, Heat & Sound, 2 - Electricity & Magnetism, 3 - Optics.

You will also have to know how to solve problems, not just to pass the course since that is almost entirely what the grade is based on, but also to ensure that you understand the concepts precisely enough to be able to apply them in different situations in different contexts and to understand the relevance to reality of the principles you apply while ignoring other factors as not important.

When solving problems, always remember that you dealing with aspects that are regarded as essential to the analysis. Think about what it is you are or might be omitting (e.g., friction or air resistance, or non-rigidity, or 'edge effects', or accuracy in dimensions, etc.). If you only think in terms of the numbers for the variables in the equations you will never understand the role and possible significance of other factors and how they relate to your concepts. In particular you will never understand the nature of engineering physics (or applying physics to reality at all) in which one must understand what aspects are significant to a problem and how they affect the accuracy of your result when you omit them. Without that understanding you would again be left with manipulating concepts as floating abstractions.

From a more philosophical perspective on the basic laws of physics, in addition to Ayn Rand's Introduction to Objectivist Epistemology in general philosophy, you should read these articles illustrating how some basic concepts and principles of physics are conceptually and experimentally justified:

  • Harriman, "Induction and Experimental Method", The Objective Standard, Vol 2, No 1, spring 2007. On Galileo's kinematics and Newton's optics.
    Harriman, "Isaac Newton: Discoverer of Universal Laws", The Objective Standard, Vol 3, No 1, spring 2008. On the principles of dynamics and of gravitation.

These articles are chapters from his forthcoming book due out this summer.

You should also listen to Leonard Peikoff's recorded lecture series on the history of western philosophy. This is not about philosophy of science or physics, but it does trace out the evolution of the main questions of philosophy, including those in metaphysics and epistemology, showing how philosophers over time tried to answer and were influenced by their predecessors and what the Objectivist answers are. This evolution has deeply influenced the way the theory of physics is formulated and presented today, so the course provides a lot of insight into why things you are told often don't make sense or leave you unsatisfied, with the clues you need from Objectivism on how to make sense of it.

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I say this without exaggeration: a degree in Physics is (from my experience) literally the most challenging degree you can obtain as an undergraduate student. No other field of study can compare in terms of level of abstraction, mathematical rigor, and overall complexity.

http://xkcd.com/435/ :)

Perhaps it is no representative sample, but back at Cambridge, the smartest students did maths, with Physics (natsci with specialization in maths & physics) being the dropout course for those unable to handle the abstraction of maths undergrad. There WERE exceptional students in physics undergrad; but they usually graduated by 19, and finished their (British) PhD (equ. to US MA) by 21. The hardest working scientists were those doing biochemistry and related topics, and I would argue they were also seriously bright; the sheer learning and unexplored territory in that field is astonishing and it was really a case of how much could they learn about the world in the shortest amount of time.

That being said, physics is THE field that allows you to learn about the world, and as such is a very great subject to study (perhaps, had I done it, I wouldn't now be in finance :)). But every undergrad thinks their degree is the hardest. I did Engineering, and used to think it was fairly hard; until I saw one of the "top 10" students attending mathematics undergrad lectures instead of ours because he was bored.

Engineering was fun but ultimately frustrating precisely because of the lack of abstraction due to the sheer time limits and amount an engineer has to learn in order to be able to make stuff.

I've also scraped the surface of truly astonishing work in the William Gates building (computer science) but do not even have the mental abilities to comprehend what these guys are doing. As they say, computer science is as much about computers as astronomy about telescopes...

(come on, you exposed yourself to this :))

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You will eventually realize that studying physics on a 'high school' level can be more conceptually difficult than college physics because of the deliberate attempts to dumb it down and to avoid using more mathematics that is required to more simply and easily understand it. That approach only exacerbates the bad approach of memorizing rules.

Yes, yes, and yes. The sooner you can start learning Calculus, the better. If there is one good thing you can take out of highschool, it would be learning the basics of Calculus as thoroughly as possible. If they don't teach it, rent a Calculus book and try learning it in your spare time.

Without Calculus, teachers are often forced to teach Physics through "lies" without even realizing it.

For example, they teach us to memorize religiously that work is equal to force times displacement. This is only true for some forces, not all. Work is the line integral of force along the path of motion, period.

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"Field," in turn, is just a region in which there is a force of some kind, such as a gravitational force or an electrical force. Quantitatively, the total force is usually proportional to the mass (for gravity) or charge (for electrical force), so the intensity of the field is measured as force per unit of mass, or force per unit of charge.

To be picky, the field concept is used for many other things besides forces. In Thermal Physics you have the concept of "radiation field", and in Classical Electrodynamics you have the electric potential which is a scalar field, the magnetic vector potential which is a vector field, and the Poynting Vector which is another vector field.

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I say this without exaggeration: a degree in Physics is (from my experience) literally the most challenging degree you can obtain as an undergraduate student. No other field of study can compare in terms of level of abstraction, mathematical rigor, and overall complexity.

http://xkcd.com/435/ :)

Yeah, that's a great one!
Perhaps it is no representative sample, but back at Cambridge, the smartest students did maths, with Physics (natsci with specialization in maths & physics) being the dropout course for those unable to handle the abstraction of maths undergrad. There WERE exceptional students in physics undergrad; but they usually graduated by 19, and finished their (British) PhD (equ. to US MA) by 21. The hardest working scientists were those doing biochemistry and related topics, and I would argue they were also seriously bright; the sheer learning and unexplored territory in that field is astonishing and it was really a case of how much could they learn about the world in the shortest amount of time.

That's interesting; where I studied Math was typically easier than Physics for undergrad study. For a full Math degree they didn't take any more advanced math courses than what we were required in Physics, but they had to take lots of "Math theory" that seemed almost like pseudophilosophy.

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You will eventually realize that studying physics on a 'high school' level can be more conceptually difficult than college physics because of the deliberate attempts to dumb it down and to avoid using more mathematics that is required to more simply and easily understand it. That approach only exacerbates the bad approach of memorizing rules.

Yes, yes, and yes. The sooner you can start learning Calculus, the better. If there is one good thing you can take out of highschool, it would be learning the basics of Calculus as thoroughly as possible. If they don't teach it, rent a Calculus book and try learning it in your spare time.

Second that. Calculus is incredibly easy to learn, also. I think you can cover most of it in 5-10 hours with a good book. Never understood why they stretch it over 2 years at school.

In fact the Cambridge engineering department, as a joke, taught calculus (starting with the derivative of 2x^2 and up to triple integrals and simple partial derivs) in a 2 hour course they called "refresher". But some of our profs were a bit insane :)

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Second that. Calculus is incredibly easy to learn, also.
Calculus is not incredibly easy to learn for everyone.
I think you can cover most of it in 5-10 hours with a good book. Never understood why they stretch it over 2 years at school.
Most people can't learn calculus by just sitting down with a book for 5-10 hours. To really understand anything takes a lot of time and effort.

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Second that. Calculus is incredibly easy to learn, also.
Calculus is not incredibly easy to learn for everyone.
I think you can cover most of it in 5-10 hours with a good book. Never understood why they stretch it over 2 years at school.
Most people can't learn calculus by just sitting down with a book for 5-10 hours. To really understand anything takes a lot of time and effort.

You are right of course, but I suspect the thread starter is smart enough if he is asking that kind of questions already. As for understanding in detail, sure, but the initial learning can be seriously sped up compared to what they do at school.

The way I have found myself learning (calculus included) was to speed through to cover a method, and then move on to the next level. E.g. to understand integration of x^2, cover the integration of cos (x^2), etc.

Made concepts stick. I found that there wasn't much of a limit other than mental in the speed of learning. I've tried this method with kids and it works - once you tell them it's easy they do it. I remember Trachtenberg taught mental maths to mentally retarded children, who would easily become able to do 6 digit operations without writing anything down, in seconds; I do think drive compensates for any lack of intelligence. It is definitely the case that some of the most successful people I know are barely above average in IQ, compensating with extraordinary work ethic.

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"Field," in turn, is just a region in which there is a force of some kind, such as a gravitational force or an electrical force. Quantitatively, the total force is usually proportional to the mass (for gravity) or charge (for electrical force), so the intensity of the field is measured as force per unit of mass, or force per unit of charge.

To be picky, the field concept is used for many other things besides forces. In Thermal Physics you have the concept of "radiation field", and in Classical Electrodynamics you have the electric potential which is a scalar field, the magnetic vector potential which is a vector field, and the Poynting Vector which is another vector field.

That is more than "picky". A 'field' is any quantity that depends on position, from displacement fields, to velocity fields, and much more.

But none of that tells you what the abstraction refers to in physics, which is usually the question when someone wants to know, for example, what a simple electrostatic field 'really is'. That is an epistemological question about the nature of the universal and requires multiple levels of abstractions and concepts of methods. You have to start with lower level field concepts like a simple gravitational field and build from there. A field is not "a region in which ..." That confuses the location of the field phenomenon with the field.

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Second that. Calculus is incredibly easy to learn, also.
Calculus is not incredibly easy to learn for everyone.
I think you can cover most of it in 5-10 hours with a good book. Never understood why they stretch it over 2 years at school.
Most people can't learn calculus by just sitting down with a book for 5-10 hours. To really understand anything takes a lot of time and effort.

You are right of course, but I suspect the thread starter is smart enough if he is asking that kind of questions already. As for understanding in detail, sure, but the initial learning can be seriously sped up compared to what they do at school.

The way I have found myself learning (calculus included) was to speed through to cover a method, and then move on to the next level. E.g. to understand integration of x^2, cover the integration of cos (x^2), etc.

Made concepts stick. I found that there wasn't much of a limit other than mental in the speed of learning....

How easy calculus is depends on the scope and depth of understanding. You can easily spend a year or two on theoretical understanding of theorems, principles, limit concepts, and a large collection of analytically exact and approximate techniques and the time it takes to become accustomed to creatively using them -- or you can much more quickly learn a few simple things about derivatives and integrals of polynomials and a few other simple functions -- or you can waste a lot more time on only the latter. To say that calculus can be learned in 10 hours of hard work is to invoke a very limited idea of the scope of the subject.

Patrik should learn as much as he can in a reasonable amount of time like a few months about the basic concepts and some methods for applying them so he will be familiar with their use in elementary physics. Taking a full college calculus course later will also then be easier because he will have a base of the fundamental ideas to build on and will not be slowed down by becoming acclimated to 'foreign' ideas right from the beginning.

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Without Calculus, teachers are often forced to teach Physics through "lies" without even realizing it.

For example, they teach us to memorize religiously that work is equal to force times displacement. This is only true for some forces, not all. Work is the line integral of force along the path of motion, period.

I would argue that one still needs to know the simple "force multiplied by displacement" relation in order to understand where the line integral comes from. The line integral is just a summing up of a potentially infinite number of very small "slices," each one of which is treated as having a constant force and linear change of displacement (though varying from one slice to the next). In the limit, as the number of "slices" increases indefinitely and the size of each "slice" becomes correspondingly smaller and smaller, the result is the line integral. (This illustrates how the theory of limits is a crucial bridge between algebra and calculus.)

The technology of measuring forces is a fascinating subject in itself, also. If one wants to know how strong a mechanical force is, one can compare it to the weight (at a defined latitude and elevation on the Earth) of a fixed standard, i.e., a fixed-size object of specific composition. There is actually a government agency in the U.S. that houses a wide range of such "standards" of measurement. Manufacturers of measuring instruments can go there to obtain "transfer standards" which can then be used to calibrate the measuring instruments, while maintaining a fully traceable "calibration trail" all the way back to the NBS. Springs of all kinds tend to make good measuring devices for general use, after being calibrated by means of a traceable calibration trail.

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