# patrik

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8

Thank you!
2. ## Basic Concepts in Physics

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.
3. ## Basic Concepts in Physics

Back again. They obviously didn't joke when they said university physics was hard. Boy... I've found some satisfying answers to the initial questions here. I'll try and list them for "scrutiny" here later if I have the time. For now I'll just say that I keep running into these conceptual problems every now and then, an example being with "energy". My book on thermodynamics says it is about to define energy (Two times it proudly says this), then in the following section it that energy is "such a rich concept" that it therefore can have "many different meanings" and then proceeds to not define it but say that "It can change it's forms" and then lays out the the old formulas for kinetic and potential energy - and expects the reader to now know what energy is. (Or not? I'm starting to think maybe both authors and teachers don't really care if there is any actual understanding.) I asked my teacher, after he had "Defined" energy the same way on a lecture: "What is energy?" (The thing which he'd been talking about for two hours) and the answer he gave was "It's hard to say precisely what it is". I mean come on... Makes me angry just thinking about it. Anyhow I got from Harry Binswanger the definition of energy as "The ability to do work", and perhaps you said so here also. That sounds right and that's what I'm using. At the moment I'm trying to figure out the difference between Energy and Exergy. And I'm also trying to learn the two first laws of thermodynamics. And thermodynamic reversibility - that one is hard because I almost think the definition of it looks like a blatant contradiction. Btw what do you mean by this?
4. ## Limits

I found what ewv said here to be very helpful. I too had a big aha-moment when I in my first college calculus course came across a definition of limit as a fixed value, and not just some value that is approached but never reached. It seems to me as though a limit is a value which a function differs less and less from when the variable approaches some number. In that way I can view it as fixed. But I'm not sure yet If i've got it 100%. This is what ewv said (Fourth paragraph): I get stuck here because I don't get what is meant by precision, nor what is the relationship between the variables N, n or e. I mean for instance are they values of the function or the variable?
5. ## Basic Concepts in Physics

Right now it seems to me that you need the concept Force to form the concept Mass. And you need a unit of Mass, to derive a unit of Force. Is that how it is?
6. ## Basic Concepts in Physics

So the attributes force and mass are everywhere and easy to conceptualize, right? But what is the relation between those concepts? Can you form them separately or does mass, as I suspect, depend on a conceptualization of force? (You can determine how hard you push or pull something, and see how much it moves, then apply approximately the same amount of force on something else and see that it doesn't move as much - it's more massive - then you can conceptualize mass.) And I'm trying to figure out how you arrive at the the units. It's become clear to me that all mechanical units are derived from 'Mass', 'Length' and 'Time'. And so the unit Newton is dependant on these. The meter and second is quite obvious how you establish. But the kilogram; how do you abstract the mass from the standard SI-unit for 1 kg, without using a unit for force? (which requires a unit for mass, which becoms circular) I'm assuming they use m=F/a but I'm not sure. The standard kg is just an instance of something pushing downward a certain amount so it looks like it is a unit of force, and not mass. Could someone explain this?
7. ## Basic Concepts in Physics

There is a lot of value here. I've read through it all and will go back to it. So far in school I've covered basic circuitry, electricity, momentum, circular motion and gravity, waves, light, springs, parabolic thowing-curves, electric and magnetic fields. I haven't made up my mind on relativity yet, that's for later. I don't buy the idea that space exists and can curve, however Einstein himself said that spacetime wasn't space or time (or even a mixrture) but something entierly different. So I have to understand the entire argument before I can go either way with it, and that will take some time. About Harriman, I think most of what he says is valuable. I'm really looking forward to his book The Logical Leap this summer. I found this on youtube. - it's Harriman talking about space and realtivity. Very interesting and it's relevant to your discussion.
8. ## Basic Concepts in Physics

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'?